Author: orbenr

Sea lions eat prey bigger than their heads

By Rachael Orben, Assistant Professor (Senior Research), Seabird Oceanography Lab

There aren’t that many Steller sea lions that call the Pribilof Islands home. The way I learned to spot them, was to watch for excited groups of kittiwakes materializing out of nowhere, just off-shore. The kittiwakes circle, periodically dipping down to grab something from the water. Then a sea lion head emerges from the water and more often than not, the lion would have a flatfish. The sea lion whips the fish back and forth, splashing and causing pieces to break off. The kittiwakes drop down and pick up the little bits. The black-legged kittiwakes that we were tracking with GPS dataloggers often flew in laps around the island (Paredes et al. 2012, 2014); stopping at the outflow of the fish processing plant, and perhaps, also on the lookout for foraging Steller sea lions to pick up an extra snack.

A Steller’s sea lion with a small flock of kittiwakes viewed from the cliffs of St. George Island. Photo: R. Orben

Gape limitation

At first glance, one might assume that sea lions are gape-limited. What do I mean by this? Basically, gape limitation means that predators can’t consume anything that doesn’t fit into their mouths whole. This idea is typically considered in the context of fish but does come up in seabird and marine mammal ecology from time-to-time. Specifically, when a predator doesn’t have a method for pulling its prey apart so is required to consume it whole. For instance, seabirds that feed their chicks whole fish can encounter this problem (e.g. puffins, terns, murres). Small chicks can starve if parents are bringing back fish that are too large to fit into the gape of the chick.

Gape limitation of cartoon fishes. Art: R. Orben

Sea lions and their eclectic large prey

I don’t know if the flatfish consumed by the Steller sea lions are too large to be swallowed whole. But, I do know that they use a strategy known as ‘shake feeding’ (Kienle et al. 2017). This feeding style is important as it offers the behavioral mechanism that allows sea lions to consume prey that exceeds their gape limitations. When sea lions are observed eating large prey it often occurs in surprising circumstances, but I suspect this foraging tactic is fairly common (e.g. Hocking et al. 2016). I have compiled a few examples both from the scientific literature and the internet to see.

Observations

Galapagos sea lions and tuna. This example is amazing and features Galapagos sea lions working together to herd tuna into shallow lagoons. Compared to the sea lions, the tuna are large! (When you are done looking at the amazing photos please return and finish reading my blog.)

Besides the flatfish I observed Steller’s sea lions eating, there is an observation of a Steller catching a shark (the online photo account stops before the shark is consumed so I don’t know what happened) and catching and consuming northern fur seal pups (Gentry & Johnson, 1981).

Gentry & Johnson 1981, include a particularly gruesome description of the predation events: “Fur seal young most often were caught by the abdomen and eviscerated with a sideways shake of the sea lion’s head (in the same manner used to tear apart large fish). Sea lions most often dived with the prey still moving and surfaced father offshore, usually beyond the kelp beds, with the pup motionless. …Larger sea lions broke apart their prey under water, surfacing only to swallow large bits of tissue. Smaller sea lions vigorously shook the carcass at the surface using the same sideways snapping motion used to eviscerate the pup at capture.”

Photo of a Steller Sea Lion and its prey: a northern fur seal pup. Photo: Gentry & Johnson 1981.

I found a fascinating series of photographs of a California Sea Lion and a Mola Mola. It is a little hard to tell what is going on, but the photographer has labeled his photos “A California Sea Lion kills, and eats, a Mola Mola”.

Southern sea lions consume large prey in the form of penguins and more surprisingly fur seals. Thus far these observations are limited to males.

A southern sea lion on the hunt for penguins early in the morning at Volunteer Point, Falkland Islands. Photo: R. Orben
South American Sea Lion killing a small fur seal. Photo R. Orben
Sea lions eating a fur seal. Photo R. Orben
After a kill caracaras and vultures picked the carcasses clean. Photo R. Orben
Patrolling sea lion. Photo R. Orben

Eating octopus

Sea lions also use shake feeding to consume octopus. Though an octopus might be smalled enough to be eaten in one gulp, they are a smart and agile prey whose tentacles make them harder to swallow. I have seen Southern sea lions flipping octopus at the surface using the ‘shake feeding’ mode. Once I watched a young juvenile bring one ashore to eat (photos below). Perhaps foraging on octopus offers some opportunities for learning how to eat large prey?

A southern sea lion shaking an octopus just off-shore Turn Island, Falkland Islands. Photo: R. Orben 2014
A juvenile southern sea lion bringing an octopus ashore on Kidney Island, Falkland Islands. Photo: R. Orben 2018
Photo: R. Orben 2018
Photo: R. Orben 2018

References

Gentry, R. L., & Johnson, J. H. (1981). Predation by sea lions on northern fur seal neonates. Mammalia, 45(4), 423–430. http://doi.org/10.1515/mamm.1981.45.4.423

Hocking DP, Ladds MA, Slip DJ, Fitzgerald EMG, Evans AR (2016) Chew, shake, and tear: Prey processing in Australian sea lions (Neophoca cinerea). Marine Mammal Sci 33:541–557

Kienle SS, Law CJ, Costa DP, BERTA A, Mehta RS (2017) Revisiting the behavioural framework of feeding in predatory aquatic mammals. Proc Biol Sci 284:20171035–4

Paredes R, Harding AMA, Irons DB, Roby DD, Suryan RM, Orben RA, Renner HM, Young R, Kitaysky AS (2012) Proximity to multiple foraging habitats enhances seabirds’ resilience to local food shortages. Mar Ecol Prog Ser 471:253–269

Paredes R, Orben RA, Suryan RM, Irons DB, Roby DD, Harding AMA, Young RC, Benoit-Bird KJ, Ladd C, Renner H, Heppell S, Phillips RA, Kitaysky AS (2014) Foraging Responses of Black-Legged Kittiwakes to Prolonged Food-Shortages around Colonies on the Bering Sea Shelf. PLoS ONE 9:e92520

Midway Atoll: the next two weeks at the largest albatross colony in the world (two years later)

By Rachael Orben, Assistant Professor (Senior Research), Seabird Oceanography Lab

This February I had the opportunity to spend two weeks at Midway Atoll National Wildlife Refuge in the Papahānaumokuākea Marine National Monument. I was there to GPS track black-footed and Laysan albatross during their short chick-brooding foraging trips. Two weeks is just enough time since the albatross are taking short trips (3-5 days) to feed their rapidly growing chicks.

My first visit to Midway (2016 blog post) occurred right as the black-footed albatross chicks were hatching (quickly followed by the Laysan albatross chicks). This time, we arrived almost exactly when I had left off. The oldest chicks were just about two weeks old. This shift in phenology meant that, though subtle, each day offered new insights for me as I watched chicks transform into large aware and semi-mobile birds. By the time we left, unattended chicks were rapidly multiplying as the adults shifted to the chick-rearing stage. During chick rearing, both parents leave the chick unattended and take longer foraging trips.

Our research goal was to collect tracking data from both species that can be used to address a couple of research questions. First of all, winds can aid, or hinder albatross foraging and flight efficiency (particularly during the short brooding trips). In the North Pacific, the strength and direction of the winds are influenced by the ENSO (El Niño Southern Oscillation) cycles. The day after we left Midway, NOAA issued an El Niño advisory indicating weak El Nino conditions. We know from previous work at Tern Island (farther east and farther south at 23.87 N, -166.28 W) that El Niño improves foraging for Laysan albatrosses during chick brooding, while during La Niña reproductive success is lower (Thorne et al., 2016). However, since Midway is farther north, and farther west the scenario might be different there. Multiple years of GPS tracking data are needed to address this question and we hope to return to collect more data next year (especially if  La Niña follows the El Niño as is often the case).

We will also overlap the tracking data with fishing boat locations from the Global Fishing Watch database to assess the potential for birds from Midway to interact with high seas fisheries during this time of year (project description, associated blog post). Finally, many of the tags we deployed incorporated a barometric pressure sensor and the data can be used to estimate flight heights relative to environmental conditions such as wind strength. This type of data is key to assessing the impact of offshore wind energy (Kelsey et al., 2018).

How to track an albatross

To track an albatross we use small GPS tags that we tape to the back feathers. After the bird returns from a foraging trip, we remove the tape from the feathers and take the datalogger off. Then we recharge the battery and download the data!

Catching a tagged albatross that just returned from its foraging trip. Photo V. Ternisien
Recording data. Photo V. Ternisien
Getting ready to remove the GPS datalogger. Photo V. Ternisien
The GPS datalogger was taped to the back feathers of the bird. To remove the tag we simply peel off the tape. Photo V. Ternisien

This research is a collaboration between Lesley Thorne (Stony Brook University), Scott Shaffer (San Jose State University), myself (Oregon State University), and Melinda Conners (Washington State University). The field effort was generously supported by the Laurie Landeau Foundation via the Minghua Zhang Early Career Faculty Innovation Fund at Stoney Brook University to Lesley Thorne.

My previous visit to Midway occurred just after house mice were discovered attacking incubating adult albatrosses. Since then, a lot of thought and effort had gone into developing a plan to eradicate mice from Midway. You can find out more via Island Conservation’s Midway blogs and the USFWS.
Dancing.
There is always something happening in a seabird colony.
Red-tailed tropicbird
From left to right: A Laysan albatross, a hybrid, and a black-footed albatross.
The colony was never quiet. Even at night.
A GPS tagged Laysan albatross.
Habitat restoration.
A short-tailed albatross sitting next to his chick (the large black chick the his right).
References

Kelsey, E. C., Felis, J. J., Czapanskiy, M., Pereksta, D. M., & Adams, J. (2018). Collision and displacement vulnerability to offshore wind energy infrastructure among marine birds of the Pacific Outer Continental Shelf. Journal of Environmental Management, 227, 229–247. http://doi.org/10.1016/j.jenvman.2018.08.051

Thorne, L. H., Conners, M. G., Hazen, E. L., Bograd, S. J., Antolos, M., Costa, D. P., & Shaffer, S. A. (2016). Effects of El Niño-driven changes in wind patterns on North Pacific albatrosses. Journal of the Royal Society Interface, 13(119), 20160196. http://doi.org/10.1098/rsif.2016.0196

Surprises from the field: Winter in the Falkland Islands

By Rachael Orben, Assistant Professor, Seabird Oceanography Lab

Fieldwork often comes with the unexpected. It is the reason why field work is so exciting – not only discovering something new about a species and ecosystem, but it is also often the catalyst for the development of novel ideas and projects. However, designing a successful field campaign to a new location (and acquiring funding) requires preconceived expectations that are not too far off from reality. Working with colonial breeding seabirds and pinnipeds has its advantages since these animals are predictably found at their colonies during the breeding period.  However, breeding failures can be worse than expected (see my blog on red-legged kittiwakes) and as I just learned, sometimes almost everything can be surprising.

At the end of August, I returned from a 6-week winter field campaign on Bird Island in the Falkland Islands led by Dr. Alastair Baylis a Senior Research Fellow at the South Atlantic Environmental Research Institute. We were there to study the fine-scale foraging ecology of South American fur seals. Despite a healthy research community in the Falklands, very little is known about South American fur seals in the region. Our time on Bird Island was probably the first time people had been on the island in winter since the days of sealing.

So, what did I find surprising?

I will list them here from slightly mundane to the very surprising.

1) First of all, it was winter and I expected it to be cold.

This is probably a case of me not doing my pre-field season research, but it was pleasantly not as cold as I expected. Generally, the temperatures were above freezing, which made doing everything much easier. Of course, I still wore lots of layers and drank lots of hot drinks, but overall it was fairly mild.  It was also less windy and less rainy than I had imagined and we had some beautiful sunny days.

Our last night on the island. Still bundled Up. Photo (c) Kayleigh Jones
Inside our tent. Photo: (c) Kayleigh Jones
Sunrise over west Falkland. Photo (c) R. Orben
2) I had hay fever!

Not something usually anticipated for winter field work, but the tussac grass was flowering and that left me with itchy eyes, a stuffy nose and lots of sneezes. I should mention that tussac grass is everywhere and many of the tussacs are taller than a person!

Tussac grass in bloom. Photo (c) Rachael Orben
A tiny tussac. Photo (c) Rachael Orben
We camped in the middle of the tussacs. Photo (c) Kayleigh Jones
In the tussacs. Photo (c) Rachael Orben

Now for the science surprises.

3) FEMALE Fur Seals took foraging trips That were much longer than we had anticipated.

We had a couple of females leave the colony and go on foraging trips for 10 days, others for ~2 weeks, and others for over 3 weeks! Previous work on the island indicated that female fur seals might take 4.1­ +/- 2 day trips (Thompson et al. 2003). Fortunately, we were on the island for the long-haul (6-weeks shower free) so we were able to wait them out and retrieve the tags (and the data) when the females came home. The differences in trip duration could simply reflect annual changes in prey availability, but we know very little about what fur seals are eating, especially during the winter (Baylis et al. 2013).

Female fur seal nursing pup. Photo (c) Kayleigh Jones
South American Fur Seal with biologging tags attached. She went on a foraging trip, returned to the island and then we recaught her to remove the devices. Photo (c) Rachael Orben
Nursing female fur seals and pups at the top of the hill. Photo (c) Rachael Orben
4) albatrosses were attending their colony.

As a reminder, this was the middle of winter. Generally, black-browed albatrosses do not return to their colonies until September since they lay eggs in October (Strange, 1992). There weren’t many birds the day we arrived in mid-July (n=9), but even so, that was odd enough that I began taking photos of the colony each day with the plan to count birds and quantify colony attendance.

Black-browed albatrosses on their nest in late winter. Photo (c) Rachael Orben
Just a small proportion of birds were in attendance. Photo (c) Rachael Orben
Black-browed albatrosses sitting on their nests. Photo (c) Rachael Orben

…and for the most surprising of all…

5) South American Sea Lions males were killing and eating female South American fur seals!

We were slow to realize what was happening since it was so unexpected. After we deployed our tracking tags on fur seals we spent many hours at the colony simply observing. We started to see things that didn’t quite make sense. Females cautiously approaching the water. Male sea lions hanging out in the water. Then Dr. Baylis saw a male sea lion go up into the colony and grab a pup and eat it! Shortly after that, we saw two male sea lions chase a female out of the water and up the hill towards the colony. One male eventually came back down to a tide pool with a female he had killed in his mouth. From that point, it because very clear what was happening and we saw multiple kills.

It is unknown how often male southern sea lions eat fur seals, but it has been observed in the Falklands before, both in the 1970s and in more recent years (Gentry & Johnson 1981).  Worldwide, sea lions are known to occasionally eat fur seal pups (Gentry & Johnson 1981, Harcourt 1993, Bradshaw et al. 1998), but people have rarely observed sea lions predating females.

Sea lions on patrol. Photo R. Orben
Giant petrels following a sea lion who has just made a kill. Photo R. Orben
South American Sea Lion killing a small fur seal. Photo R. Orben
Lion-in-wait. Photo R. Orben
After a kill caracaras and vultures picked the carcasses clean. Photo R. Orben
Patrolling sea lion. Photo R. Orben
Sea lions eating a fur seal. Photo R. Orben 
Our three scientific surprises are really what field work is all about. We came home with the tracking data we were hoping for and we came home with something arguably more valuable. We can use these new observations to make informed hypotheses about how marine predators fit into the ecosystem in ways that before our visit to Bird Island we would have never have expected. Hopefully, we will have a chance to go back!
Seal team 3. Kayleigh Jones, Rachael Orben, and Alastair Baylis.
Looking out towards the fur seals. Photo: Kayleigh Jones
References

Baylis AMM, Arnould JPY, Staniland IJ (2013) Diet of South American fur seals at the Falkland Islands. Marine Mammal Sci 30:1210–1219

Bradshaw CJA, Lalas C, Mcconkey S (1998) New Zealand sea lion predation on New Zealand fur seals. New Zealand Journal of Marine and Freshwater Research 32:101–104

Gentry RL, Johnson JH (1981) Predation by sea lions on northern fur seal neonates. Mammalia 45

Harcourt R (1993) Individual variation in predation on fur seals by southern sea lions (Otaria byronia) in Peru. Canadian Journal of Zoology 71:1908–1911

Strange, IJ (1992) Field Guide to the Wildlife of the Falkland Islands and South Georgia (Collins Pocket Guide)

Thompson DR, Moss S, Lovell P (2003) Foraging behaviour of South American fur seals Arctocephalus australis: extracting fine scale foraging behaviour from satellite tracks. Mar Ecol Prog Ser 260:285–296

When are seabirds at their breeding colonies?

By Rachael Orben PhD., Research Associate in the Seabird Oceanography Lab and GEMM Lab

When are seabirds at their breeding colonies? 

As the weather warms-up, and spring arrives to the Oregon Coast, seabirds (and seabird biologists) are starting to get busy. One vital task is monitoring annual trends in seabird abundance. Identifying whether seabird populations have increased, declined or remained stable over time is an important ecosystem indicator and a conservation management metric.

Most seabirds arrive at breeding colonies just prior to egg laying, and then leave after their chicks fledge. Within this time seabirds reunite with their mate, defend their nesting territory, build a nest, lay eggs, and feed their chicks. Biologists often count individual birds or nests to estimate population size. This method works well when birds are nesting in easy to observe locations. However, seabirds often nest on inaccessible cliff faces, or in underground burrows. How do we count these difficult to reach and difficult to see species?

This is an important challenge, because burrow nesting seabirds comprise roughly 45% of all seabird species, yet typically little is known about colony specific population trends of these species. 

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Metrics of abundance

For these cases where counts of seabirds are logistically difficult, the alternative metric of colony attendance becomes important.  Like count data, a meaningful index of abundance can be compared from year to year to follow population changes. For burrow nesting seabirds, this is probably the best method to understanding population dynamics. But, abundance metrics, counts of birds or calls, are complicated and can be influenced by multiple factors, including weather, predators, time of day, time of the breeding cycle, and proportion of non-breeders in a population. (Harding et al. 2005, Cadiou 2008, Mallory et al. 2009).

I conducted a quick search for scientific papers in the Web of Science database and found that although colony attendance is assessed in seabird studies, it is currently nowhere near as “hot” a research topic as tracking the spatial movements of seabirds. This pattern makes sense when you consider the importance of understanding where birds find their food, and that the tracking technology to do this was not available until the early 2000s (Burger & Shaffer 2008). We are still at a point where new species are being tracked as technology improves, and movement patterns are revealing the many facets of seabird ecology.

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Developing Technology

Technology has also improved for monitoring colony attendance. Instead of sitting at a puffin colony in the wind and rain making repeated counts throughout the day, biologists can now use cameras or even acoustic recorders to record activity (Huffeldt & Merkel 2013, Borker et al. 2015). Then the data processing and counting happen back in the office (with a warm cup of coffee in hand). Through automated processing of sound and image files suddenly seabird colony attendance becomes a “Big Data” problem (see red-legged kittiwake detection with Azure ML Workbench).

Selected images from a trail camera set up to monitor Leach’s storm petrels. Photos: Seabird Oceanography Lab.

There is much we still don’t know about when and why seabirds attend their breeding colonies, and these new tools have much to offer in terms of data quantity. With dense datasets, it becomes possible to tease apart multiple factors that sometimes make interpretation challenging. Colony attendance data has many uses, including testing for anthropogenic effects, understanding seabird responses to weather, and detecting changes in populations over time. If you are reading this consider using cameras or acoustic recorders to monitor colony attendance at your favorite seabird colony!

References

Borker AL, Halbert P, McKown MW, Tershy BR, Croll DA (2015) A comparison of automated and traditional monitoring techniques for marbled murrelets using passive acoustic sensors. Wildlife Society Bulletin 39:813–818

Burger AE, Shaffer SA (2008) Application of Tracking and Data-Logging Technology in Research and Conservation of Seabirds. The Auk 125:253–264

Cadiou B (2008) Attendance off breeders and prospectors reflects the quality off colonies in the Kittiwake Rissa tridactyla. Ibis 141:321–326

Harding AMA, Piatt JF, Byrd GV, Hatch SA, Konyukhov NB, Golubova EU, Williams JC (2005) Variability in Colony Attendance of Crevice- Nesting Horned Puffins: Implications for Population Monitoring (Peterson, Ed.). Journal of Wildlife Management 69:1279–1296

Huffeldt NP, Merkel FR (2013) Remote Time-lapse Photography as a Monitoring Tool for Colonial Breeding Seabirds: A Case Study Using Thick-billed Murres (Uria lomvia). Waterbirds 36:330–341

Mallory ML, Gaston AJ, Forbes MR, Gilchrist HG (2009) Factors Influencing Colony Attendance by Northern Fulmars in the Canadian Arctic. Arctic 62:151–158

 

Do I have the time?

By Rachael Orben PhD., Research Associate in the Seabird Oceanography Lab and GEMM Lab

So, there is something called work-life balance. I am still trying to find mine.

As an undergraduate it was easy. I sailed a lot and my grades suffered. In hindsight that was the best choice I could have made.  I learned to sail, spent time on the water and in the end, I think I turned out ok. Following that I spent ~7 years working as a field technician in remote, stunningly beautiful places, with lots of seabirds. I would sum these years up as having very little life balance with lots of experience.

From there I started grad school. At age 29, I relearned how to live in a town and bought my first car. I spent 5.5 years in grad school, but 14 months of this time were spent in the field (not all for my PhD research). During the last phase of my PhD I was often too mentally exhausted on the weekends to even consider trying to write or to analyze data.  I tracked my working hours with RescueTime and I found that after a weekend at play my Monday at work was often very focused and productive. Then through the week my productivity would drop.

That seemed promising. Playing more equaled more efficient work hours. The tales are true.

And then I started post doc life.  A new town, more rain, and more projects that come with deadlines. For the most part, my attempts for a work-life balance went out the window as I adjusted to the new locale. I still do field work and within that experience I can catch my academic breath – while working just as hard.

Evening on High Bluffs, St. George AK

One can read ad nauseam about struggles academic scientists have balancing work and life. There is lots of sage advice out there (e.g. here) and dismay with a system that asks so much of a person (here). As I continue on this career path I know that demands on my time will only become more and more frequent. There is a part of me that likes the idea of curling up on a rainy Saturday morning and crunching out some data analysis even though in the long run this probably isn’t a good approach. And maybe that is the problem – I love most of what I do!

For now, I am still learning. What do I focus on? What do I spend my time on? How do I meet deadlines without a dose of panic? How do I restrain my growing to-do list?

**In order to make sure that I didn’t over or under achieve on this blog post I asked the internet ‘how long should a blog post be?’  It turns out the answers are varied.  But somewhere between 700 and 1,600 words is a good target. I made it to 488.  Today there is a dog that wants a walk, a talk to be written, a manuscript to revise, dinner to cook…

Walking along the Oregon Coast.

 

Meeting to disentangle factors influencing albatross bycatch in the deep-set Hawaii Longline Fishery

By Rachael Orben PhD., Research Associate in the Seabird Oceanography Lab and GEMM Lab

Seabird bycatch is a global problem (e.g. Anderson et al 2011). Humans like eating fish and seabirds do too. Fishing vessels provide a food source for seabirds through discards, bait, and target fish. Different types of fishing gear pose different risks for seabirds. The good news is there are things that we can do to decrease these risks.

Albatrosses and petrels are particularly vulnerable to being hooked by longlines as the baited hooks are set overboard. Albatrosses and petrels are long lived (e.g., Wisdom the 65-year-old Laysan Albatross) and have a limited number of off-spring. Therefore fishery mortalities can have devastating impacts on populations if left unchecked. Currently all 22 species of albatrosses have IUCN statuses ranging from Near Threatened to Critically Endangered.

North Pacific Albatrosses

Longlines are used to catch a number of target species including tuna, swordfish, halibut, black cod, and toothfish. Just like the diversity of species this type of fishing gear is used to catch, there are a number of ways to set long-lines and ways to mitigate seabird bycatch and a method that works well in one instance may not work so well in other places. Tori Lines (a.k.a. streamer lines), side setting, night setting, faster sinking lines, and discard regulations are a few of the methods used.

Tori lines work by scaring birds away from baited longline hooks while they sink. Once the hooks sink past a few meters albatrosses are not able to reach them. Photo by Ed Melvin/Washington Sea Grant

In early November, I had the opportunity to attend a workshop in Honolulu, Hawaii hosted by the Western Pacific Regional Fishery Management Council. The workshop was held due to a dramatic increase in black-footed albatross bycatch by the Hawaii deep-set longline fishery in 2015 and 2016 (see the figure below). It was our job to figure out why, or more realistically pave the path for future analysis and data collection to answer this question.

Recently Leigh Torres and I were funded by the NOAA Bycatch Reduction Engineering Program to characterize fine-scale fishery-albatross interactions using previously collected albatross tracking data and tracks of fishing boats processed in real time by Global Fishing Watch. The workshop provided the perfect opportunity for me to learn more about the Hawaii longline fisheries.

Reasons for Albatross Bycatch

Rates of bycatch can change due to many factors, including where or when the fish are being caught, subtle choices made by fishermen, changes in seabird distributions, changes in prey of fish or seabirds, and so on. So, it can be very challenging to pin-point the exact reasons for an increase in bycatch. But, across the North Pacific, 2015 and 2016, were very strange years oceanographically. There was the warm water phenomena known as ‘the Blob’ along with a strong El Niño, and a positive Pacific Decadal Oscillation (PDO). So perhaps, bycatch levels will drop off again as we move into a La Niña, but perhaps not. It is good to know that fishery managers and scientists are paying attention.

Implications

From the perspective of the fisherman in the Hawaiian longline fleet, albatrosses are hardly ever caught; they are pulled in at a barely perceptible level of less than one bird per set and only from about December to July. Although one occasional dead bird among the menagerie of fish doesn’t seem like much, it can add up: there are ~140 boats in the deep-set longline fleet, that set 40-52 million hooks a year, plus the multiple other fisheries and fleets encountered by albatrosses across the North Pacific, and enough albatrosses could be killed to make a difference in their population numbers. And, we need to also consider the cumulative impacts since fisheries aren’t the only threat  (e.g., sea level rise, storm surges, introduced predators; see Bakker et al 2018).

Inspecting the Catch

On the morning of the last day of the workshop we took a field trip to the Honolulu Fish Market at Pier 38 in Honolulu where the Hawaiian long-line fishing vessels dock to offload and sell their catch. We checked out some of the boats, watched fish being craned off a vessel into a large cart and went inside the cooler room to see where the fish are auctioned.

In the cooler room, the catch from one vessel was laid out on brilliant blue pallets. The tails of each tuna were sliced so the deep pink color of the meat could be assessed. A core sample of each fish was laid out on an identification tag. Then the auctioneer and the buyers visited each fish, rapidly bidding on a price per pound. Their quick words were basically incomprehensible to my untrained ear.

The prize-catch of the fishery, and the fish that gets the highest price per pound, is the big eye tuna. A number of other large and beautiful pelagic species are also caught and sold including: long and narrow marlins, with their bills cut off for packing, side table size pomfrets, speckled white with red accents; and the distinctive blunt headed mahimahi, with yellow bellies. Once the fish are sold, they are moved out of the auction room, packed and loaded into the trucks that whisk them away toward markets and restaurants in Hawaii, the U.S. Mainland, and beyond.

Sustainable management of these commercially valuable fish is dependent on a better understanding of their pelagic ecosystem, including when, where, and why albatrosses interact with fishing vessels. Hopefully, our current research project will help to answer some of these questions.

Early morning on Pier 38
Hawaiian longline vessels
Back deck of a Hawaiian longliner
Offloading the catch
Auctioning the fish
Big-eye tuna
mahimahi
Little bill fish
Yellow-fin tuna
Pomfrets
Tuna being shipped out

Where are the eggs? Studying red-legged kittiwakes in a time of change

By Rachael Orben, Research Associate, Department of Fisheries and Wildlife, Oregon State University

In late May, I returned to St. George Island, Alaska to study the foraging ecology of red-legged kittiwakes using a mix of high-tech biologging tags, physiology measurements, and observations.  The study was designed to identify differences in behavior and physiology between birds that reproduce successfully and birds that don’t and then to see how this might carry over to the winter season (and vice versa).  Things didn’t go as planned.

A red-legged kittiwake on St. George Island. Photo C. Kroeger

This was my fourth spring on the island, and like prior seasons we arrived in late May, when birds should be building nests. However, unlike previous seasons, red-legged kittiwake’s didn’t look like they had done much nest building. I was accompanied by Abram Fleishman, a superstar MS student from San Jose State who is studying the winter spatial ecology of red-legged kittiwakes in relationship to mercury concentration in their feathers.

We immediately set about recapturing birds that had carried geolocation data loggers over the winter. We wanted to catch as many as possible before eggs were laid, so that their blood samples would represent the pre-lay period. The weather was wonderful, so it wasn’t until three weeks after we arrived that we had our first day-off. It was at about this time that I finally lost my optimism and realized the majority of red-legged kittiwakes were not going to lay eggs. By late June kittiwakes are usually incubating eggs. We only saw a handful of eggs and very few of these were being incubated. Most birds didn’t even build nests, or if they did, the nest was dismantled by other birds when the nest building pair didn’t stick around to guard their pile of mud and moss.

Nests in 2016. Laying success was also low in 2016, but even if birds didn’t lay many pairs built nests.
Same cliff (and birds) without nests in 2017.

When I designed the study, I thought collecting enough data to answer my questions about successful versus failed breeders would be hard, since failed breeders would be challenging to work with and red-legged kittiwakes typically have high breeding success, meaning that sample sizes of failed breeders would be small. Instead our three seasons occurred with progressively worse breeding success and we will now have to shift the focus of our analysis to see if we can find differences between birds that laid eggs and birds that didn’t, if we have the sample sizes! With ~80% laying success in the 9 years preceding the beginning of our study in 2015, this is something I would never have expected! The egg laying failure of 2017 is unprecedented in the productivity monitoring time series collected by the Alaska Maritime Wildlife Refuge.

Seabirds are often touted as indicator species of marine health (Cairns 1988, Piatt et al 2007), and while there are always caveats and additional questions to be answered, seabirds are reliant on the ocean for food and observing their behavior and condition tells us something about how easy (or hard) it is for them to find food.

So, what do I think the red-legged kittiwakes told us this year? I think they were squawking loud and clear, that they were not able to find myctophid fishes within their foraging range to the south and west of the Pribilofs. Myctophids are small fatty mesopelagic bioluminescent fish that come to the surface at night where red-legged kittiwakes catch them.

Besides just observing the laying failure, we were able to GPS track a few birds, collect a few diet samples, catch birds for blood and feather samples, and resight banded individuals. It is these pieces of information that I will be analyzing in the coming months to try to understand why some individuals were able to lay eggs during our study years, while most were not.  These years should also help us understand what capacity red-legged kittiwakes have to cope (or not) with changes in prey availability. However, after three years, I still don’t know what a ‘good’ year looks like for red-legged kittiwakes. Fingers crossed next season is finally a decent year for this sentinel seabird of the pelagic Bering Sea.

Pre-lay foraging trips of red-legged kittiwakes in 2015.
Pre-lay foraging trips of red-legged kittiwake in 2017. Two birds were heading north when their GPS loggers stopped recording.

You can read more about our red-legged kittiwake research in a series of blog posts written for the Seabird Youth Network, a partnership between the Pribilof School District, the Aleut Community of St. Paul Island, the City of St. Paul, Tanadgusix Corporation, the St. George Traditional Council, St. George Island Institute, the Alaska Maritime National Wildlife Refuge, and the wider scientific community. The network creates opportunities for youth to learn about seabirds with the aim of building local capacity for the collection of long-term seabird monitoring data on the Pribilof Islands.

The pier in front of the Village seabird cliffs. Photo A Fleishman
View from High Bluffs. Photo A Fleishman
Standing around. Photo C. Kroeger
Resting on the rocks. Photo C. Kroeger
Landing
Retrieving a GPS logger
St. George Village
Setting a foot snare
Team selfie! Photo A Fleishman
Steller sea lions
High Bluffs
The elusive white lousewort
Resting in the sun.
Chuuchii (least auklets) over the village.
Release
Geolocation data loogers.
Evening on High Bluffs
High Bluffs at sunset
High Bluffs in the Fog
High Bluffs
Early Season. Photo A Fleishman
red-legged kittiwakes
red-legged kittiwakes in the sun

Simple behavior classification of tracking data with residence in space and time

By Rachael Orben PhD., Postdoctoral Scholar in the Seabird Oceanography Lab and the Geospatial Ecology and Marine Megafauna Lab 

At 2pm, Jan 3, our paper entitled “Classification of Animal Movement Behavior through Residence in Space and Time” was published. At 14:03 I clicked on the link and there it was, type-set and crisp as a newly minted Open Access scientific contribution.

So, what is this paper about? It presents a simple – yes simple – method of identifying simple behaviors states in two-dimensional animal tracking data (think latitude and longitude). Since the paper is open access you can go find the methods there. Categorizing these “dots on a map” into behaviors allows us to ask questions about how often, why, when and where simple behaviors happen. These behaviors really are simple (hopefully the somewhat grating repetitiveness of the word ‘simple’ has driven that point home by now!). We are identifying three basic, but fundamental, states:

1) transit, characterized by fast somewhat straight line movement from a to b,

2) a sedentary state characterized by relatively more time spent in an area with little distance traveled (such as resting behavior) and

3) an active state characterized by lots of time spent in an area where an animal is also moving around a lot and covering a lot of ground.

This new method, that we termed Residence in Space and Time (RST), can assist the fast-growing, sophisticated, big-data generating, conservation-orientated field of animal movement ecology. One of the first hurdles is data exploration and visualization. Modern ecologists deploy tracking devices that collect location data remotely to understand animal distribution and behavior. But at first glance tracks (like the figure below) can look like spaghetti dinner. Identifying movement behaviors can help to us see patterns in the tangles.

24 GPS tracks of grey-headed albatross incubation foraging trips; tracked from Campbell Island, New Zealand.

So how might this method work? First, let’s start with a track. Below is a very short foraging trip from a thick-billed murre tracked with a GPS logger during chick rearing from St. Paul Island in Alaska (see Parades et al 2015).

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A thick-billed murre (Uria lomvia), St. Paul Island, Alaska.

The track below has points every second and we can imagine the murre flying from the colony, landing on the water, and then diving (indicated by the lack of GPS position data when the bird dives below the water to forage). Then the bird flies back to the colony to feed its chick. This trip is roughly 14 minutes long.

murretrack

So I can take this track and run RST to identify three behavior states. As color-coded below, the black points indicate transit, red indicates relatively stationary behavior, and blue indicates points where the bird was flying in a less direct manner than pure transit potentially circling around before landing and moving between dives. The high resolution of the GPS data really helps us to understand how this bird was moving. Such behavior information is easily conserved in a high-resolution track like this. Though in this case, the bird did a lot of transiting and only exhibited different movement behaviors in the vicinity of the two dives.

murretrack_1sec_rst-copy

Logging locations at 1-second intervals is a stretch for the battery life of these miniaturized GPS loggers (~15g), and more often than not we would like the loggers to last much longer than 14 mins. So instead of 1 second we typically have tracks with less frequent locations. To me, this is akin to taking a 1-second track and then taking off my glasses and trying to see the same behaviors. Deciphering behavior states becomes a bit (or a lot) fuzzier. In the case of this murre track, when we down-sample the locations to every 10 seconds much of the resolution of this track is lost (see plot below). What happens when we run RST?

murretrack_10sec_rst-copy

As you can see some of the behavior is maintained and some of it is a bit fuzzier.

A good rule of thumb is that if a behavior happens faster than the sampling interval the logger is recording at, then the behavior is not recorded. Seems simple, but it is an important consideration when programming loggers and designing animal movement studies. For murres, these quick trips to forage for their chicks are easily lost even at a 5-minute sampling interval, which is often used in seabird tracking studies where the birds are at sea for days. Often we work with such lower resolution location data and, instead of one trip from one bird, we have many trips from many individuals. RST allows a fast way to quickly and accurately identify simple behaviors in order to help with initial data exploration efforts and for answering more complex questions such as behavior specific habitat models.

So, if you have some tracking data – of birds, marine mammals, or your dog! – you can learn how RST works (basically by summing up time and distance covered within a circle). I keep an updated version of the R code, a short guide, an example dataset on a GitHub repository: https://github.com/raorben/RST.

Here is the spaghetti from above (tracks of Grey-headed albatrosses) with the behavioral states labeled using RST:  93,481 points and this behavior classification took only 14 seconds to run!  albatrosstracks_rst

Midway Atoll: Two weeks at the largest albatross colony in the world

By Rachael Orben, Postdoctoral Scholar, Seabird Oceanography Lab & Geospatial Ecology of Marine Megafauna Lab, Oregon State University

In January I was extremely lucky to accompany my former PhD advisor, Scott Shaffer to Midway Atoll National Wildlife Refuge in the Papahānaumokuākea Marine National Monument as part of my job as a postdoc working in Rob Suryan’s Seabird Oceanography Lab. We were there with the dual purpose of GPS tracking Laysan and Black-footed albatrosses as part of Scott’s long-term research and to collect fine-scale data on flight behavior to develop collision risk models for wind energy development (in other areas of the species ranges such as Oregon). Here are my impressions of this amazing island.

So many albatrosses! Our approximately four hour flight from Honolulu to Midway landed at night and as we stood around on the dark tarmac greeting the human island residents I could just make out the ghostly glistening outlines of albatrosses by moonlight. But I had to wait until the following morning to really take stock of where I had suddenly landed: Midway Atoll, the largest albatross colony in the world. This was my first trip to the Northwestern Hawaiian Islands, but I have been to other albatross colonies before and Midway is most definitely different.

First of all, it was hot(ish)!

Secondly, I was amazed to see albatrosses nesting everywhere. Unlike the southern hemisphere colonies I have visited, the albatrosses aren’t restricted to their section of the island or even nesting as close to each other as possible. Instead there are nests literally everywhere there might be enough loose substrate! Birds nest in the middle of the roads, in the bike racks (bikes are an easy quick means of transportation), along the paths, next to the extremely loud generator, near piles of old equipment, and around buildings. Hawaiian albatross nests are not much to look at compared to the mud pedestal nests of the southern hemisphere mollymawks (see the photos below) and are often made of just enough sand and vegetation to keep the egg in place. There are no aerial predators of these birds, beyond the occasional vagrant peregrine, and certainly nothing that might rival the tenacity of the skuas in the southern hemisphere. Perhaps it is this naiveté that has lead to their willingness to nest anywhere.

It may also be this naiveté that has facilitated the following unfortunate turn of events. Just before I arrived, the USFWS and a crew of volunteers had just finished up the annual albatross count. During their counting sweeps they noticed injured adults incubating eggs. After setting out trail cams, suspicions were confirmed. The introduced mice on Midway have discovered that albatrosses are a source of food. House mice are known to prey on albatross chicks on Gough and Marion Islands in the South Atlantic (more information here – warning graphic photos), but to my knowledge this is the first time that they have started eating adult birds. You can read the USFWS announcement here. The plane that I flew out on brought in people, traps, and resources to deal with the situation, but stay tuned as I fear this saga is just beginning.

Finally, and on a further less than positive note, I went to Midway fully aware of the problem that plastics pose to these birds and our marine ecosystem, but there is something to be said for seeing it first hand. The chicks were very small when I was there so I didn’t see any direct impacts on them, but see below for photos of carcasses of last year’s fledglings with plastic filled stomachs. Instead, it was the shear amount of random plastic bits strewn around the island and buried layers deep into the sand that struck me. I learned that sometimes the plastic bits are glow-in-the-dark! Sometimes fishing lures have batteries in them – I am not sure what they are used to catch – do you know? And toothbrushes are very common. All of the plastic that I saw among the birds arrived in the stomach of an adult albatross. All-in-all the experience gave me renewed inspiration for continuing to reduce the amount of plastic that I use (click here for more information on albatrosses and plastic, and here and here for info on marine plastic pollution in general). I collected interesting pieces to bring home with me (see the photos below), but it is a non-random sampling of what caught my eye. I left many many plastic shards where they were.

I have written mostly about the birds, but Midway is full of human history. As I biked along the runway, or past the old officer quarters, I often found myself wondering what all these albatrosses have seen over the years and what they might witness in the future. Two weeks was really just a blink-of-an-eye for an albatross that can live over 40 years (or longer like Wisdom the albatross). I was terribly sad to leave such a beautiful place, but I came home with amazing memories, photos, and gigabytes of data that are already giving me a glimpse into the world of albatrosses at sea.

Laysan albatross.
Weighing an albatross.
Measuring wing area.
Albatrosses on the left, infrastructure on the right.
Albatrosses in the wind.
Passing through.
Out along the runway.
Back on the nest.
Rain from Charlie Barraks.
Catching rain drops.
Feed me.
Preening after the mate switch.
Bird weighing and tagging equipment.
Switching takes some coordination when both birds want to brood the chick.
Dancing.
In step, and on their tippy-toes.
Fields and fields of albatrosses.
Laysan albatross and chick.
Laysan albatross equipped with a GPS data logger.
On the way to the runway.
Dusk arrival of Bonin petrels.
A pair of Laysan albatrosses.
Dawn on Eastern Island.
Red-footed booby, Eastern Island.
Frigatebird, Eastern Island.
Curious white tern.
Feeding.
Sign for the Midway Mall.

Recap: 2nd World Seabird Conference

By Rachael Orben, post-doc

I have just returned home from attending the 2nd World Seabird Conference held in Cape Town, South Africa. My bags are still only half unpacked as I roll back into the work world of emails, planning field-work, report writing and data analysis. I am still very jet-lagged and the cool crisp Oregon air feels strange after so recently being in the dry heat of Africa. And here comes the rain! (Oh, and should I mention that bit of sickness that always seems to creep up behind you when you travel?)

The conference was a 4-day affair that filled my days from 8:30 am until sometime after 8:30 pm. Talks, poster sessions, and a really great Early Career Scientist evening – the organizers did an excellent job squeezing so much in. Of course a conference also involves visiting with colleagues and networking….and with roughly 600 conference participants from 53 countries, I had my work cut out trying to catch up with friends and colleagues! It was amazing to have so many seabird researchers and so much seabird science in one place.

So with all the science going on, what did I learn? Well, seabird scientists have certainly embraced the use of small electronic devices in the form of GPS loggers and GLS loggers (geolocation loggers that use light levels to calculate approximate locations – think sailors and celestial navigation). To give you a taste, follow this link to a short article on BirdLife’s Global Seabird Tracking Database.

BirdLife International: 5 million data points for the world's seabirds provided by 120 research institutes (www.seabirdtracking.org)
BirdLife International: 5 million data points for the world’s seabirds provided by 120 research institutes (www.seabirdtracking.org)

This is really just the beginning, and the exciting thing is seabird scientists are getting into the more nuanced questions of seabird spatial ecology. How do birds navigate at sea? Where do non-breeding birds forage? Where do fledglings go? Do birds return to the same places to forage (spatial fidelity), both when they constrained to their breeding colonies and while on migrations? How does this change through an individual’s lifetime? Why do some individuals in a population return to the same foraging locations while others don’t? As it turns out, though the ocean might appear featureless to us, seabirds know where they are at-sea and are able to return to the same places to forage – which they do depending on all sorts of things including what species they are, predictability of prey, individual personality, and likely a few more things.

Seabird conservation was also a large and pervasive theme. However, I can’t really do the entire conference justice here. So check out #WSC2 on twitter for the posts. You can go back in time and get a flavor for many of the talks as there are 1000s of tweets!

You might ask – what is the value of traveling half way around the world to talk about seabirds? And indeed there is much discussion about the carbon cost of scientific conferences. I am not saying the WSC is the perfect model, but it does have one thing in its favour as a newly established conference: It’s infrequent occurrence. The first World Seabird Conference was held in Victoria, Canada in 2010 and the next one will happen in 2020. I wonder how seabird science will change over the next five years?!

To stay globally connected in the meantime Seabirders are experimenting with on-line conferences. I participated in the first one, held on Twitter, and I really enjoyed it and learned a lot. You too can check it out at #WSTC1 and stay tuned for #WSTC2.

After the conference I took a break from seabirds and went to explore the terrestrial world of South Africa with my parents. It was a wonderful trip and I am so glad my parents came and joined me!

IMG_5818 copy IMG_6020 copy notaseabird Lions IMG_5136 copy