Sunday, July 10, 2011

A Bristle-thighed What?

I suppose that this would be a suitable moment to provide a touch of background information on one's reasons for being dumped over thirty miles from the nearest group of bipedal apes for two months...then again, maybe such pleasures require no justification.  At any rate, I've met enough people (even birders!) who have never heard of Bristle-thighed Curlews and/or Bethel, Alaska (a much more forgivable travesty), prompting me to fill in a few blanks before continuing with my ramblings.

From May 7 to June 16 of this summer I had the incredible experience of living in the southwestern Nulato Hills of the Yukon Delta National Wildlife Refuge, the second largest National Wildlife Refuge in the country and one of its most remote locations still in existence.  Rather than mirroring the nearby expanses of pond-dappled coastal tundra to the west or the prodigious spruce forests of the great Andreafsky Wilderness to the east, these hills foster a unique combination of extensive drainage networks bordered by willows with large, intervening tracts of lichen-mat tundra.  Given the novel circumstances of the landscape, it should not come as a surprise that this region supports the largest breeding population of North America's rarest and most specialized shorebird -- the Bristle-thighed Curlew.  Indeed, the only other known (viable) population of these birds exists in a very similar landscape to the north on the Seward Peninsula.


Allen Creek (Field Site)

Given the scarcity of suitable breeding habitat for this species, combined with the scabrous, isolated nature of their required habitat, two major issues stand to retard proper conservation of curlews -- a lack of habitat and a lack of information concerning the biology of curlews.  Indeed, although the species was discovered in 1789 during James Cook's expeditions of Oceania, the first nest was not discovered until 1948 -- a date that is extremely late for the majority of known species.  In light of this, the Alaska Fish and Wildlife Service and Ph.D candidate, Jake Jung developed a set of goals for a three-year study of the Nulato Hills curlew population, which, roughly, are as follows:

1)  Assess the current breeding density of curlews in the Nulato Hills for comparison to previous years in order to determine the stability of the population in the face of conservation threats such as predation by introduced predators on the wintering grounds, subsistence harvesting on wintering and breeding grounds, and, of course, climate change.  The last assessment of both populations indicated that the global population hovers around 10,000 individuals, with 6,000 birds present in the Nulato Hills and 3,000 juvenile birds undergoing a three-year, flightless molt throughout Oceania.

2)  Color band as many individuals as possible.  This becomes particularly important for study of individual behavior on the breeding grounds, but also in determining the significance of population-based "clustering" throughout Oceania (very small sample sizes indicate that curlews from the Nulato Hills population tend to winter on northern islands, while those from the Seward Peninsula tend further south).  This latter point has fascinating implications for possible reproductive isolation between the two populations.  Indeed, a recent assessment of genetic variation between the two populations shows that birds can be accurately assigned to a population of origin based on six nuclear microsatellite loci (Talbot et al. 2004).

3)  Expand on the current life history data on Bristle-thighed Curlews.  Even to this date, relatively little study has been devoted to this species, making any information that we could obtain extremely valuable.  This includes everything from arrival dates and nesting phenology to habitat selection and foraging ecology.  One of the major components of field work under this topic was sampling invertebrates (curlew food) on known territories.

4)  Survey avifauna of the Nulato Hills.  Again, given the rare occurence of people in this region, data on all species is hard to come by.

I hope that serves as a semi-adequate introduction to the project.  More curious details of curlews themselves are to come in future posts, so don't fret!

Talbolt, Sandra L., Judy R. Gust, George K. Sage, Robert E. Gill, Lee T. Tibbitts, Richard B. Lanctot, and Brian J. McCaffery. "Population Differentiation of Breeding Bristle-thighed Curlews (Numenius Tahitiensis)." (2004): 1-12. Web. 10 July 2011.

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