Why are we monitoring?
Many marine birds rely on habitats and prey associated with the nearshore ecosystem of Alaskan coastlines. These species are top-level consumers of fish and marine invertebrates, such as mussels, clams, snails, and limpets. Because of these characteristics, these birds are good indicators of change in the coastal marine ecosystem. Our monitoring focuses on birds that have trophic links to the nearshore food web, such as sea ducks (harlequins, Barrow’s goldeneye, mergansers, and scoters) and black oystercatchers that consume benthic invertebrates, as well as other types of marine birds (e.g., pigeon guillemots, blacklegged kittiwakes, and cormorants) that occupy other marine food webs or habitats. Monitoring these various guilds simultaneously improves our ability to discriminate among potential causes of change in seabird populations and the nearshore ecosystem. For example, some of the species we monitor were impacted by the Exxon Valdez oil spill and exhibited protracted recovery periods as a consequence of lingering oil in nearshore habitats. Public concern exists for the welfare of marine birds because they are currently affected by an array of human activities. Marine birds can also provide windows into processes in marine ecosystems that are difficult to measure directly, such as change in forage fish abundance.
Where are we monitoring?
We monitor marine birds across a broad swath of the northern Gulf of Alaska within the area affected by the Exxon Valdez oil spill. Study regions include Kenai Fjords National Park (KEFJ), Kachemak Bay (KBAY), and Katmai National Park and Preserve (KATM) (Note: Western Prince William Sound monitoring is conducted by the Prince William Sound Marine Bird Population Trends project. We estimate density and distribution of a variety of marine species along coastal transects that are surveyed annually in summer. These same transects are surveyed during March, primarily to estimate density and distribution of sea ducks and other wintering birds in KATM and KEFJ.
How are we monitoring?
In KATM, KEFJ and KBAY, ecologists conduct skiff-based surveys along coastal (nearshore) habitats. We collect data that provide baseline information on species composition, distribution, and density for populations of marine birds and mammals that occur in nearshore waters. Summer surveys are conducted annually and winter surveys are conducted in either KATM or KEFJ in alternate years as weather permits. Marine bird surveys have been conducted in KATM since 2006, KEFJ since 2007 and KBAY since 2018.
SCIENTISTS CONDUCT NEARSHORE MARINE BIRD SURVEYS IN KENAI FJORDS NATIONAL PARK. PHOTO CREDIT: JIM PFEIFFENBERGER, NPS.
What are we finding?
Long-term monitoring of nearshore marine birds in the northern Gulf of Alaska shows variable trends across species and regions. In general, species that rely on benthic prey, such as sea ducks, have remained stable or increased in some areas following the Pacific marine heatwave, with winter densities of species like Barrow’s goldeneye remaining stable or increasing in recent years.
Barrow’s goldeneye winter density (#/km2) estimates across two of the four Gulf Watch Alaska regions: Katmai National Park and Preserve (KATM) and Kenai Fjords National Park (KEFJ). Surveys in each region are carried out every other year as opposed to annually due to logistical and personnel constraints.
Marine bird responses to environmental change appear closely tied to prey availability and foraging conditions. Increases in benthic prey, such as mussels, may have supported stable or increasing trends in some species, while others that rely on pelagic prey may be more sensitive to changes in ocean conditions that affect forage fish.
Overall, these patterns highlight the importance of food web dynamics in shaping marine bird responses to changing ocean conditions. Because marine birds integrate changes across multiple components of the ecosystem, they provide valuable indicators of ecosystem status and broader shifts in energy flow.