Identifying demographic changes is important for understanding population dynamics. However, this requires long-term studies of definable populations of distinct individuals, which can be particularly challenging when studying mobile cetaceans in the marine environment. We collected photo-identification data from 19 years (1992-2010) to assess the dynamics of a population of bottlenose dolphins (Tursiops truncatus) restricted to the shallow (\textless7m) waters of Little Bahama Bank. This population was known to range beyond our study area, so we adopted a Bayesian mixture modeling approach to mark-recapture to identify clusters of individuals that used the area to different extents, and specifically estimated trends in survival, recruitment and abundance of a "resident" population with high probabilities of identification. There was a high probability (p = 0.97) of a long-term decrease in the size of this resident population from a maximum of 47 dolphins (95\% Highest Posterior Density Intervals, HPDI = 29-61) in 1996, to a minimum of just 24 dolphins (95\% HPDI = 14 - 37) in 2009; a decline of 49\% (95\% HPDI = -5\% to -75\%). This was driven by low per-capita recruitment (average ˜ 0.02) that could not compensate for relatively low apparent survival rates (average ˜ 0.94). Notably, there was a significant increase in apparent mortality (˜5 apparent mortalities vs. ˜2 on average) in 1999 when two intense hurricanes passed over the study area, with a high probability (p = 0.83) of a drop below the average survival probability (˜0.91 in 1999; ˜0.94 on average). As such, our mark-recapture approach enabled useful inference about local dynamics within an open population of bottlenose dolphins; this should be applicable to other studies challenged by sampling highly mobile individuals with heterogeneous space-use.
Read More: http://www.esajournals.org/doi/abs/10.1890/12-0021.1
%0 Journal Article
%1 fearnbach_photographic_2012
%A Fearnbach, Holly
%A Durban, John William
%A Parsons, Kim Michelle
%A Claridge, Diane
%D 2012
%J Ecological Applications
%K Tursiops capture-recapture, cetacean, check, effects, home mixture model, odontocetes, posterior predictive random range, residents,
%R 10.1890/12-0021.1
%T Photographic mark-recapture analysis of local dynamics within an open population of dolphins
%U http://www.esajournals.org/doi/abs/10.1890/12-0021.1
%X Identifying demographic changes is important for understanding population dynamics. However, this requires long-term studies of definable populations of distinct individuals, which can be particularly challenging when studying mobile cetaceans in the marine environment. We collected photo-identification data from 19 years (1992-2010) to assess the dynamics of a population of bottlenose dolphins (Tursiops truncatus) restricted to the shallow (\textless7m) waters of Little Bahama Bank. This population was known to range beyond our study area, so we adopted a Bayesian mixture modeling approach to mark-recapture to identify clusters of individuals that used the area to different extents, and specifically estimated trends in survival, recruitment and abundance of a "resident" population with high probabilities of identification. There was a high probability (p = 0.97) of a long-term decrease in the size of this resident population from a maximum of 47 dolphins (95\% Highest Posterior Density Intervals, HPDI = 29-61) in 1996, to a minimum of just 24 dolphins (95\% HPDI = 14 - 37) in 2009; a decline of 49\% (95\% HPDI = -5\% to -75\%). This was driven by low per-capita recruitment (average ˜ 0.02) that could not compensate for relatively low apparent survival rates (average ˜ 0.94). Notably, there was a significant increase in apparent mortality (˜5 apparent mortalities vs. ˜2 on average) in 1999 when two intense hurricanes passed over the study area, with a high probability (p = 0.83) of a drop below the average survival probability (˜0.91 in 1999; ˜0.94 on average). As such, our mark-recapture approach enabled useful inference about local dynamics within an open population of bottlenose dolphins; this should be applicable to other studies challenged by sampling highly mobile individuals with heterogeneous space-use.
Read More: http://www.esajournals.org/doi/abs/10.1890/12-0021.1
@article{fearnbach_photographic_2012,
abstract = {Identifying demographic changes is important for understanding population dynamics. However, this requires long-term studies of definable populations of distinct individuals, which can be particularly challenging when studying mobile cetaceans in the marine environment. We collected photo-identification data from 19 years (1992-2010) to assess the dynamics of a population of bottlenose dolphins (Tursiops truncatus) restricted to the shallow ({\textless}7m) waters of Little Bahama Bank. This population was known to range beyond our study area, so we adopted a Bayesian mixture modeling approach to mark-recapture to identify clusters of individuals that used the area to different extents, and specifically estimated trends in survival, recruitment and abundance of a "resident" population with high probabilities of identification. There was a high probability (p = 0.97) of a long-term decrease in the size of this resident population from a maximum of 47 dolphins (95\% Highest Posterior Density Intervals, HPDI = 29-61) in 1996, to a minimum of just 24 dolphins (95\% HPDI = 14 - 37) in 2009; a decline of 49\% (95\% HPDI = -5\% to -75\%). This was driven by low per-capita recruitment (average {\textasciitilde} 0.02) that could not compensate for relatively low apparent survival rates (average {\textasciitilde} 0.94). Notably, there was a significant increase in apparent mortality ({\textasciitilde}5 apparent mortalities vs. {\textasciitilde}2 on average) in 1999 when two intense hurricanes passed over the study area, with a high probability (p = 0.83) of a drop below the average survival probability ({\textasciitilde}0.91 in 1999; {\textasciitilde}0.94 on average). As such, our mark-recapture approach enabled useful inference about local dynamics within an open population of bottlenose dolphins; this should be applicable to other studies challenged by sampling highly mobile individuals with heterogeneous space-use.
Read More: http://www.esajournals.org/doi/abs/10.1890/12-0021.1},
added-at = {2017-01-09T13:57:26.000+0100},
author = {Fearnbach, Holly and Durban, John William and Parsons, Kim Michelle and Claridge, Diane},
biburl = {https://www.bibsonomy.org/bibtex/2cf7abe7dde03d0054a55291285e894d4/yourwelcome},
doi = {10.1890/12-0021.1},
interhash = {6b445305bf5e83930f7c4673256eab80},
intrahash = {cf7abe7dde03d0054a55291285e894d4},
issn = {1051-0761},
journal = {Ecological Applications},
keywords = {Tursiops capture-recapture, cetacean, check, effects, home mixture model, odontocetes, posterior predictive random range, residents,},
timestamp = {2017-01-09T14:01:11.000+0100},
title = {Photographic mark-recapture analysis of local dynamics within an open population of dolphins},
url = {http://www.esajournals.org/doi/abs/10.1890/12-0021.1},
year = 2012
}