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Shorebirds and invertebrate distribution on delta mudflats along the Beaufort Sea


May 2011 - December 2015


Quality foraging habitat for shorebirds is determined by the abundance of benthic invertebrates, but can also be influenced by lagoon water levels that can inundate the delta making the habitat inaccessible to shorebirds. Most of the change in water level on delta mudflats comes from wind driven waves. If wind patterns are consistent then available habitat is predictable, but changes in tide due to westerly storms can be significant and may inundate the whole delta for several days. Climate change may change the frequency of storms and seems to have changed the intensity of the storms by increasing the size of waves because the reduced amount of ice results in fewer impediments to wave build up. This has the potential to change the availability of shorebird feeding areas, making the occurrence of this habitat less predictable to birds during the post-breeding period.

In addition to quantifying invertebrate resources, the study will assess whether the resources available to shorebirds are sufficient to prepare the birds for their fall migration. A functional response model will be used for this assessment based on the capture rate and handling time modeled against invertebrate abundance.

This study will survey the shorelines and consist of taking core samples for laboratory analysis for chemical analysis, population structure, numbers of individuals, and diversity of populations from the interstitial spaces within the littoral zone of coastlines along the Beaufort Sea.

The specific objectives of this study are to:
1. Quantify the spatial and temporal distribution of benthic invertebrates at coastal lagoons and river deltas along the Beaufort Sea coast within the USFWS Arctic Refuge at 3 sites associated with the coastal lagoons at the Jago, Okpilak, and Canning Rivers.
2. Assess the chemical footprint to characterize the sources of the suspended sediments.
3. Assess whether patterns of invertebrate abundance and distribution correspond to foraging shorebird abundance and distribution.
4. Develop a model describing the connection between wind patterns and water levels on the mudflat and sediment dispersion that can be used to assess available foraging habitat for shorebirds.
5. Assess food eaten by shorebirds through stable isotope analysis, genetics (of invertebrates collected from fecal samples).
6. Assess whether shorebirds respond physiologically to a greater abundance in food resources through body condition measurements and increased triglyceride levels.
7. Assess whether available invertebrate resources in the coastal lagoons and river deltas along the Beaufort Sea are sufficient for pre-migratory fattening of shorebirds or provide information for bioremediation.

Research Products and Activities

Peer Reviewed Publications

  • Churchwell, R. T., S. J. Kendall, A. L. Blanchard, K. H. Dunton, and A. N. Powell. 2015. Natural disturbance shapes benthic intertidal macroinvertebrate communities of high latitude river deltas. Estuaries and Coasts. DOI 10.1007/s12237-015-0028-2
  • Churchwell, R. T., S. Kendall, S. C. Brown, A. L. Blanchard, T. E. Hollmen, and A. N. Powell. 2018. The first hop: use of Beaufort Sea Deltas by hatch-year Semipalmated Sandpipers. Estuaries and Coasts 41:280–292, DOI 10.1007/s12237-017-0272-8.
  • Churchwell, R. T., S. Kendall, S. C. Brown, and A. N. Powell. 2018. Will increased storm surge frequency impact food availability for Semipalmated Sandpipers Calidris pusilla at the beginning of fall migration? Wader Study 125:195-204. DOI: 10.18194/ws.00121

Technical Publications

  • Powell A. N., R. T. Churchwell, K. H. Dunton, J. G. Baguley, A. D. Kamikawa, C. T. E. Kellogg, B. C. Crump, and P. Bucolo. 2016. Sediment Characteristics and Infauna of Deltaic Mudflats Along the Alaskan Beaufort Sea. US Dept. of the Interior, Bureau of Ocean Energy Management, Alaska OCS Region, Anchorage. OCS Study BOEM 2015-045. 77 pp.Abstract |


  • Churchwell, Roy T. 2015. Stopover ecology of semipalmated sandpipers (Calidris pusilla) at coastal deltas of the Beaufort Sea, Alaska. PhD Dissertation, University of Alaska Fairbanks, Fairbanks, AK. 149 pp.


  • Churchwell, R., S. Kendall, S. Brown, and A. Powell. 2010. Shorebird use of Arctic Refuge coastal mudflats. 14th Alaska Bird Conference, Anchorage, AK.
  • Churchwell, R., A. Powell, S. Kendall, and S. Brown. 2011. Tidal influences on food availability to shorebirds on coastal mudflats of the Arctic National Wildlife Refuge, Alaska. 17th Annual Alaska Shorebird Group Meeting, Anchorage, AK.
  • Churchwell, R. and A. N. Powell. 2012. Impacts of feeding shorebirds on the invertebrate community of an arctic mudflat. 23 Oct, 15th Annual Alaska Bird Conference, Anchorage, AK.
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Current Staff

Federal Staff: 95

Masters Students: 238

Phd Students: 144

Post Docs: 54

University Staff: 239

5 Year Summary

Students graduated: 673

Scientific Publications: 1905

Presentations: 4235



  • Abby PowellPrincipal Investigator
  • Roy ChurchwellStudent

Funding Agencies



Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey