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Centre for Wildlife Ecology
Senior Supervisor:
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Biography
I grew up in Northern Virginia (which, no, is not a separate state but anybody whoās been to Virginia knows it just isnāt the same as the rest of the state). I left home to pursue my undergraduate degree at Ferrum College (also in Virginia), and ever since I have been trying to make myself and everybody else I know forget that I am a gringa with the rest of them. Giving credit where credit is due, my love of birds happened in the U.S. when I took my first field job working on breeding bird biology in the Mogollon Rim of Arizona. Once I figured out that our winter holiday matches up with the breeding season in the tropics, Christmas, much to my parentsā dismay, became a travel opportunity instead of a family occasion. Flying south for the winter soon became an annual ritual, taking me to places such as Puerto Rico and Peru. I then spent the last semester of undergrad at USFQ in Cumbayá, Ecuador, melding my love of tropical ecology, conservation, and Spanish. At this point I had a serious case of the Latin bug and moved to Tucumán, Argentina, to work on altitudinal migration in montane cloud forest (yungas) bird communities for a year and a half. I then lived on a cattle ranch in the llanos of Venezuela while working on green-rumped parrotlets, which resulted in endless comparisons between there and my parentsā cattle ranch in New Mexico. After returning to the U.S., I decided to get to know my own country for a change and worked several bird field jobs ranging from trans-gulf migration to grassland bird communities. By the end of 2000, having lived in 6 states, driven through 22 states to get there, and having put 12,000 miles on my car in one year, the search was over. It was time combine my interests in research and conservation and begin to do my own research, made one last trek adding another 3000 miles and 5 states, from New Mexico to Vancouver, BC, where I Īve come to hang my nomadic hat for a couple of years while working on my Masters in physiological and conservation ecology here at SFU.
[Click
here for a more complete list of my education, work, and
research]
M.Sc. Thesis Project
Can we use physiology to evaluate habitat quality at migration stopover sites of Western Sandpipers?
My research involves physiological information to address ecological
questions concerning the migration of the Western
Sandpiper (Calidris mauri). Westerns migrate from their
breeding grounds in the arctic to their wintering grounds in Latin America
and southern California. It takes them weeks to make this trip as
they "hop" from site to site, stopping along the way for some R&R and
to eat in order to restore fat reserves for the remaining trip. The
overall goal of my project is to use physiological data to evaluate and
compare several of these migratory stopover sites throughout the Georgia
Basin in Washington State and BC.
In evaluating these sites, the ultimate expression of site quality
in the western sandpiper is fat deposition. If a site allows
individuals to obtain a high rate of fattening, it is allowing the birds
to achieve their ultimate goal better than a site at which the birds are
not able to fatten. Previous studies have focused on mass to
evaluate condition at these sites; however this only gives us a snapshot
of one moment in time. If two populations have equal mean mass but
one population is gaining and the other is losing, the conditions of the
two populations differ considerably while the mass data alone would not
detect this.
Throughout their migratory journey, as westerns travel from site to
site and stop to refeed, they embark on a flip-flop cycle of fattening
and fasting. From a physiological standpoint, the birds are in a
constant flux of fat metabolism (long-distance flight) and deposition (re-feeding).
By-products of these processes that are detectable in the plasma
are, among others, glycerol and triglycerides respectively. Therefore,
an individual with high glycerol levels would be metabolizing large quantities
of fat and would be indicative of a state of starvation. On the other
hand, an individual with high levels of triglyceride would be laying down
a large quantity of fat and would be thought to be thriving.
My research involves using these plasma metabolite levels to determine
fattening rates of individuals and populations to give me a better idea
of the condition achieved at various sites. My overall question
is whether or not there is a site difference in fattening rates.
The first step is to see if the method is robust enough to detect a site
difference. I would also like to determine if there are seasonal
and/or annual variation within sites and whether or not fattening rates
vary according to sex and/or age.
I am also investigating the underlying factors that influence habitat quality. This includes prey availability, prey consumption, and foraging strategies at each site. To measure prey availability, I take mud cores with a modified 60 cc syringe (cores are 22cc, 40mm deep). The cores are sieved first through a 500 µm sieve (macrofauna) and then settled out 4 times and the supernatant is sieved through a 63 µm sieve (meiofauna). Both the meiofauna and macrofauna factions are identified to large taxa groups and counted. In order to have an index of food consumption, I analyze fecal samples. Birds that are waiting to be processed are kept in modified tupperware bowls that serve as birdy bathrooms, and the fecal samples are frozen and later analyzed for percent presence of taxa. The WESA is dimorphic by culmen with males having shorter bills and females having longer bills. The WESA has two general foraging strategies: peck and probe. The peck is a superficial foraging strategy by which the bill taps the surface of the mud or is barely inserted, feeding primarily on smaller organisms. The probe is a deep insertion of the bill into the mud. I make foraging observations on focal individuals of each sex and record the total number of foraging attempts per unit time and classify each attempt as surface or deep. This will allow me to compare foraging rates and strategies between sites and see if that correlates to prey populations and those sites.
A second aspect of my research is to understand the effect of diet composition on the relationship between triglyceride levels and mass gain and how that is affected by diet composition. This goal is being achieved through a series of controlled experiments on individuals in captivity.
Throughout the Georgia Basin in both Washington State and BC are several
of these sites that are used by westerns both in the northward and southward
migrations. Some of these sites support up to half a million westerns
at the peak of northward migration! Recent years have shown a decline
in shorebird numbers along their migration route. In the effort of
shorebird conservation, it is imperative to understand the impetus for
stopover site selection (thatās the million dollar question!) and to identify
which sites yield high fattening rates in the birds.
Last Update 22 Jan 2002. Contact CWE webmaster.