Wintering Ecology of Buff-Breasted Sandpipers (Tryngites subruficollis) in Southern Brazil
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Authors
de Almeida, Juliana B.
Issue Date
2009
Type
Dissertation
Language
Keywords
Brazil , Buff-breasted Sandpiper , life history , population dynamics , Tryngites subruficollis , wintering
Alternative Title
Abstract
Buff-breasted Sandpipers (Tryngites subruficollis) are a medium-sized
sandpiper that suffered a steep population decline during the last century.
Current estimates of population size are at least one order of magnitude smaller
than historical estimates. The continued decline in population size has resulted
in Buff-breasted Sandpipers being recognized world-wide as a species of critical
conservation concern. Yet, little is known about their ecology at wintering sites
and about their population dynamics. In this dissertation, I present results on
within- and among-year density trends, life-history strategy, molt, body condition
and population dynamics of Buff-breasted Sandpipers wintering in southern
Brazil. Additionally, I provide a discriminant function to accurately sex Buffbreasted Sandpipers using morphometric measures.
I estimated density trends of Buff-breasted Sandpipers at three wintering
sites, Lagoa do Peixe National Park (LPNP), Ilha da Torotama (IT) and Taim
Ecological Station (TES). Density was highest at IT, but was closely followed by
LPNP. Buff-breasted Sandpipers were absent from TES during most of the study.
Because of the consistency of use, and high densities at LPNP and IT, I suggest
that these sites be included in any management action directed toward
conservation of the species.
Results in molt schedule, as well as arrival and departure patterns at LPNP
indicated that males and females have different life-history strategies. Males
molted wing and tail feathers faster than females, finishing molt approximately
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one month before females. This difference mirrored the difference in departure
from the wintering grounds: males depart one month earlier than females.
Moreover, sex ratio at LPNP was female biased and males were more prone to
leave the site in any given month. The between-sex difference in life-history
strategy and female bias at the north end of the wintering range suggest that
sexual segregation in Buff-breasted Sandpipers is opposite to what would be
predicted by sexual segregation theory: male Buff-breasted Sandpipers winter
further south instead of further north as would be predicted.
Apparent annual survival of Buff-breasted Sandpipers is equivalent to or
higher than survival rates reported for other shorebirds. Additionally, males had
lower apparent annual survival and a higher temporary emigration rate than
females. Differences in apparent annual survival between sexes may result from
the short-term nature of this study and/or higher emigration rate of male Buffbreasted Sandpipers. Therefore, future long-term studies utilizing markrecapture techniques are critical for understanding variation in Buff-breasted
Sandpipers annual survival. This study demonstrated that wintering sites provide
the best location for estimating annual survival.
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