Apparent Survival of Pacific Black Brant Branta bernicla nigrans

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Apparent Survival of Pacific Black Brant (Branta
bernicla nigrans)

• Rebecca Bryan, Chris Cannon, Hayley Glover, Paige
  Gingrich
• Institute of Arctic Biology
• University of Alaska Fairbanks

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Pacific Black Brant

• Nest in Canadian and Alaskan arctic regions
• Winter along Pacific Coast of Washington, Oregon,
  California and Mexico

http//www.uaf.edu/news/featured/05/avian/images/
large/Black_Brant_Guards_Nest.jpg
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Distribution of Brant in North America
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Background

• 2,998 previously marked brant were sighted during
  9, one-week sampling intervals
• Sampling occasions occurred in Mexico and
  California during the winters of March 1998,
  December 1998, January 1999, February 1999, March
  1999, December 1999, January 2000, February 2000,
  and March 2000

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Goals of Study

• Determine the apparent survival of black brant
• Determine if there are changes in apparent
  survival during the winter and the rest of the
  year
• Find changes in apparent survival over time
• Find the best way to model the recapture
  probability

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Methods

• Data analyzed in Program MARK using
  Cormack-Jolly-Seber models (recaptures only)
• Best-fitting models selected using AIC weights

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• Phi(wintert)p(t)- Survival is time-specific in
  winter months, constant in non-winter months and
  recaptures is time-specific.
• Phi(wintert)p(t)- Survival is time-specific in
  winter months, constant in non-winter months and
  recaptures is time-specific.
• Phi(wintert)p(t) Survival is time-specific in
  winter months, constant in non-winter months and
  recapture is time-specific.
• Phi(seasont)p(t) Survival is time-specific
  between winters and non-winter periods, and
  recapture is time-specific.
• Phi(seasont)p(seasont) Survival is time
  specific between winters and non-winters, and
  recapture is time-specific between winters and
  non-winters.
• Phi(season)p(t) Survival is constant within
  winter and non-winter periods and recapture is
  time-specific.
• Phi(wintert)p(t) Survival is time-specific in
  winter months, constant in non-winter months and
  recaptures is time-specific.
• Phi(seasont)p(.) Survival is time-specific
  between winters and non-winters and recapture is
  constant.
• Phi(wintert)p(.) Survival is time-specific
  between winter months, constant in non-winter
  months and recapture is constant.
• Phi(season)p(.) Survival is constant between
  winter months and constant between non-winter
  months, recapture is constant.

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s
Mar-dec dec-jan jan-feb feb-mar
s
Mar-dec dec-jan jan-feb feb-mar
s
Mar-dec dec-jan jan-feb feb-mar
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Results
Table 1 Models analyzed in Program MARK along
with AIC scores
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Table 2 Apparent survival estimates with
standard error for models with highest AIC values
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Model Phi(wintert)p(T) (by 4 para)
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Model Phi(wintert)p(T) (by 3 para
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Discussion

• Best way to model capture probability
• Time Specific

-Observer -Weather -Seasonal/Yearly Change
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Discussion

• Previous Studies
• Mortality and Permanent Emigration CONFOUNDED
• March-December versus December-March
• Migration Stress, Breeding/Nesting Stress,
  Harvest Mortalities

www.ag.unr.edu/brant/ images/photos/morrobay74.jpg

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Discussion

• Better Approaches
• Sampling during summer months
• Combining band recovery data with observation
  data? Burnham model (separate perm. emigration
  mortality)
• Standardize observers as much as possible
• Account for difference in winter and non-winter
  time discrepancies

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Citations

• Photos not cited were taken from The Birds of
  North America
• Bellrose, F. C.. 1980. Ducks, geese and swans of
  North America. 3d ed. Stackpole Books,
  Harrisburg, PA
• Burnham. K.P., White. G.C. 1999. Program MARK.
• Charlesworth. B.1994. Evolution in Age-Structured
  Populations. 2nd ed. Cambridge University Press.
  Cambridge, United Kingdom.
• Reed, A., D. H. Ward, D. V. Derksen, and J. S.
  Sedinger. 1998. Brant (Branta bernicla). In The
  Birds of North America, No. 337 (A. Poole and F.
  Gill, eds.). The Birds of North America, Inc.,
  Philadelphia, PA
• Sedinger. J.S., Chelgren. N.D., Lindberg. M.S.,
  Obritchkewitch. T., Kirk. M.T., Martin. P.,
  Anderson. B.A., and Ward. D.H. 2002. Life-History
  Implications of Large-Scale Spatial Variation in
  Adult Survival of Black Brant (Branta bernicla
  nigricans). The Auk 119(2) 510 515.
• Ward, D.H., E.A. Rextad, J.S. Sedinger, M.S.
  Lindberg, N.K. Dawe. 1997. Seasonal and Annual
  Survival of Adult Pacific Brant. Journal of
  Wildlife Management. 61773-781.

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Questions????
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