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.
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.
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).
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!
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