Dramatic population declines in the Kittlitz’s murrelet: assessing the magnitude and potential causes of the decline

The Kittlitz's murrelet (Brachyramphus brevirostris) is a rare seabird that nests in recently deglaciated terrain and tends to be associated with glaciers while foraging during the breeding season. Because nest sites are inaccessible and at-sea behavior is difficult to study, very little is known about the natural history and ecology of this species; the Kittlitz’s Murrelet is arguably the least-understood bird species breeding in North America.

More than 95% of the global population is estimated to breed in Alaska, with the remainder occurring in the Russian Far East. A global population estimate using best-available data in the early 1990s was 20,000 individuals. However, survey data from two core areas (Prince William Sound and Glacier Bay) show 80-90% population declines during the past 10-20 years. In response to those declines, a coalition of environmental groups petitioned the U.S. Fish and Wildlife Service in May of 2001 to list the Kittlitz’s murrelet under the Endangered Species Act.

Because so little is known about the biology of the species, both the causes and true magnitude of this decline are unknown. Leading hypotheses explaining all or part of the decline include naturally occurring changes in food abundance, glacial recession, oil spill mortality, vessel disturbance in foraging areas, and gillnet mortality. Effective management of the species is currently impossible because of the lack of basic information about its status and ecology. We are working to address critical information needs in a multi-year study that examines (1) status of Kittlitz’s Murrelets in areas where distribution and abundance are poorly known, (2) Kittlitz’s murrelet ecology and habitat relationships in Glacier Bay, (3) the impact of vessel traffic on foraging Kittlitz’s murrelets in Glacier Bay, and (4) retrospective analysis of historical data collected ancillary to other work, focusing on diet, distribution, population trends, genetic population structure, and breeding biology. Click on this text or the photo to learn more.

Cook Inlet Seabird and Forage Fish Study (CISeaFFS):

A key to understanding seabird population dynamics is to characterize the biological responses of seabirds to fluctuations in prey abundance, distribution and quality. This long-term study forms the basis of the ABSC Seabird Project, and is designed to measure foraging (functional) and population (numerical) responses of six seabird species to fluctuating forage fish densities at three seabird colonies in lower Cook Inlet. This involves at-sea surveys (hydroacoustic, trawling, seining) for forage fish while measuring aspects of seabird breeding biology and behavior at adjacent colonies. Funded by the Exxon Valdez Oil Spill (EVOS) Trustees under the Apex Predator Experiment (APEX) program, and by USGS (including Base and MMS-OCS funds). Collaboration with Alaska Maritime National Wildlife Refuge (ANMWR), U.S. Fish and Wildlife Service (USFWS), Alaska Department of Fish and Game (ADF&G), Institute of Marine Science, University of Alaska Fairbanks (IMS-UAF) and several universities. Last year of field work was FY99. Reduced funding for write-up in FY00-01.

Analysis of historical data on trawl catches of forage fish in the Gulf of Alaska, 1953-1999:

Evidence suggests that long-term changes in forage fish communities have markedly influenced availability and quality of prey for higher predators such as seabirds and marine mammals. This study examines extensive small-mesh trawl and icthyoplankton databases for long-term variability in marine fish populations and community composition. Funded by EVOS Trustees under the APEX project. Collaboration with NMFS (Kodiak) and ADF&G (Kodiak and Homer). Reduced funding for write-up in FY00.

Ecology and demographics of Pacific Sandlance in lower Cook Inlet:

Sandlance is the most important nearshore forage fish in most of Alaska, but despite their importance there is a paucity of information on this species. In this study, we are examining seasonal distribution and abundance patterns of sandlance in Cook Inlet and Gulf of Alaska, spawning biology and behavior, growth and energetics, larval emergence and offshore distribution, and population genetics. Funded by EVOS Trustees under APEX project. Collaboration with ADF&G, NMFS, AMNWR, and Memorial University of Newfoundland. FY99 last year for field work. Reduced funding for write-up in FY00.

Effects of diet quality on postnatal growth of seabirds:

Declines of seabirds and marine mammals in Alaska may have resulted in part from changes in availability of high-quality (fatty) forage fish. This experimental study tests the hypothesis that diet quality (energy density, lipid or protein composition) constrains growth, development and survival of young piscivorous seabirds. Funded by EVOS Trustees. Collaboration with Oregon State University, Corvallis OR. Project completed. Write-up in FY00 underway (M.Sc. Thesis submitted).

Monitoring response of seabirds to changing prey availability using stable isotope analyses:

Recent advances in the use of naturally occurring stable isotopes of carbon and nitrogen to trace foodwebs is being applied to seabird communities to assess trophic dynamics in different areas of Alaska. Funded by Canadian Wildlife Service (CWS), GLOBEC and USGS. Collaboration with CWS, Saskatoon, Saskatchewan and NMFS, Seattle. GLOBEC funding ended in FY99. Reduced effort will continue in FY00.

Seabird and Marine Mammal Coordinated Investigations (SMMOCI):

Measuring seabird and marine mammal productivity, populations, and diets, hydroacoustic and trawl surveys for prey and oceanographic studies around 9 different long-term study colonies in the Gulf of Alaska, Bering Sea and Chukchi Sea. No direct USGS funding. Conducted in collaboration with AMNWR, National Marine Fisheries Service (NMFS), and IMS-UAF. Project will continue in FY00 with surveys in SE Alaska (St. Lazaria Island).

A genetic study to aid restoration of murres, guillemots and murrelets to the Gulf of Alaska:

Populations of some seabirds are not recovering from effects of the EVOS. State-of-the-art genetic techniques are being applied to determine geographic limits of species populations, detect cryptic species, identify genetic markers for specific colonies, and identify sources and sinks. Funded by EVOS Trustees, USGS and AMNWR. Collaboration with Queen=s University, Ontario, Canada. Field completed in FY99. Reduced funding in FY00 for write-up.

Physiological stress in seabirds in relation to food supplies:

Although "food stress" is commonly suggested as a source of variability in seabird productivity and populations, little is known about how changes in food availability or quality induce physiological stress in seabirds. In both field and laboratory conditions we are examining the role of corticosteroid hormones and stress in the biology of seabirds under differing food regimes. Funded by EVOS Trustees, USGS and the University of Washington. Field work will continue in FY00-01.

Survival of seabirds under differing food regimes:

Populations of seabirds in lower Cook Inlet fluctuate over time, and changes in population size reflect the sum of three processes: adult mortality, recruitment of locally-produced offspring, and the immigration/emigration of breeding adults from/to other colonies. In this project, we are measuring population trends, productivity and annual adult survival of murres and kittiwakes in relation to local food abundance at two colonies in Cook Inlet. Funded by the EVOS Trustees. Field work will continue in FY00-01.

Small Schooling Fish (SSF) and predators in Glacier Bay National Park:

Glacier Bay National Park comprises a relatively pristine marine environment, and hosts a variety of marine predators such as humpback whales and seabirds. Variability in the abundance and distribution of these predators may be linked to changes in the availability of SSF, but little is known about the biology, abundance or habitat use by SSF in the Glacier Bay ecosystem. We are studying SSF and predators using similar methods employed in the Cook Inlet Seabird and Forage Fish project, including hydroacoustic surveys, trawls, and seines to study SSF, and pelagic surveys to assess the abundance and distribution of marine predators. Funded by USGS (Base and NRPP funds), and Glacier Bay National Park. Reduced field work will take place in FY00.

Impact of native subsistence harvest on Glaucous-winged Gulls in Glacier Bay National Park:

Glaucous-winged Gull colonies in Glacier Bay National Park have been a traditional source of eggs for the local Tlingit peoples for many generations. However, little is known about the impacts of subsistence harvest on gulls. We are studying the population biology of Glaucous-winged Gulls in the Park, conducting a manipulative experimental study that will simulate egg-harvesting practices and allow us to measure the costs associated with egg-production and impacts on productivity and survival of adult Glaucous-winged Gulls, and, developing a model in which the effects of timing and intensity of egg-harvesting at the gull colony can be projected for differing harvest scenarios. Funded by Glacier Bay National Park and USGS (Base funds). Field work in FY99 and FY00. No funding after FY00.

Pelagic seabird distribution and abundance:

A wealth of data have been collected over the past three decades on the abundance and distribution of seabirds at sea in Alaska and elsewhere in the North Pacific. These include data collected under large research programs of the past (e.g., OCSEAP, PROBES, ISHTAR), and more recent projects by government agencies or universities (EVOS Trustee Council, USGS, USFWS, MMS, SMMOCI, GLOBEC, SEBSCC). We are compiling and cataloging these various datasets. We will develop a web-based database query mapping system to answer requests for pelagic data (e.g., for oil spill contingency or response planning, mitigation of fishery impacts, education, research). This project will proceed in FY00-01 with support from Royal Caribbean Settlement Funds administered by the USFWS, and collaborative support from Migratory Bird Management (Reg. 7).

Effects of food stress on reproductive performance of seabirds at Pribilof and Bogoslof Islands, Bering Sea:

Concern over declining populations of seabirds and marine mammals in the Bering Sea prompted funding by USGS to the University of Alaska to conduct studies on higher vertebrate predators in the Bering Sea. In both field and laboratory conditions we are examining the role of corticosteroid hormones and stress in the biology of Red-legged and Black-legged Kittiwakes, and Thick-billed and Common Murres at a colony this is declining (Pribilofs) and one that is increasing (Bogoslof). Funded by the UAF Bering Sea Research Grant, USGS and the University of Washington. Field work began in FY99 and will continue in FY00. In partnership with the Alaska Maritime National Wildlife Refuge (USFWS) and the Institute of Marine Science (UAF).

Protocols for long-term monitoring of seabird ecology in the Gulf of Alaska:

Some seabird populations damaged by the Exxon Valdez oil spill have not recovered, and populations will need to be monitored for many years to assess both recovery and ecological conditions affecting recovery. Detailed studies of individual seabird colonies and marine ecosystems in the Gulf of Alaska (GOA) have been conducted by the USGS and USFWS under the auspices of damage assessment and restoration programs of the EVOSTC. As we move towards long-term monitoring of populations, however, we need to develop protocols and long-term monitoring strategies that focus on key parameters of interest and that are inexpensive, practical and applicable over a large geographic area. In partnership with the Alaska Maritime National Wildlife Refuge (USFWS), this project will focus on developing protocols and monitoring strategies for implementation under the Gulf Ecosystem Monitoring (GEM) initiative being developed by the EVOS Trustee Council. Funded by the EVOSTC, USGS and USFWS.