TITLE: PALMER LTER: EVIDENCE SUPPORTING A LANDSCAPE EFFECT ON THE LONG-TERM
POPULATION TRENDS OF ADELIE PENGUINS 
AUTHORS: W.R.Fraser
DATE: 31 Aug - 4 Sep 1998
PLACE: SCAR VII International Biology Symposium in New Zealand 

William R. Fraser, Polar Oceans Research Group, Biology 
Department, 310 Lewis Hall, Montana State University, Bozeman, MT 
59717, USA. 

Explanations regarding the causal origins of long-term 
change in Adelie Penguin populations have focused almost 
exclusively on the effects of variability in the marine 
environment. Although this approach lacks neither empirical nor 
theoretical support (Trivelpiece et al. 1990; Fraser et al. 
1992), Fraser and Patterson (1997) recently proposed that 
population trends in this species may also be regulated in part by 
factors that affect the availability and quality of terrestrial 
breeding habitats. New research on breeding biology and further 
analyses of population trend data that span more than two 
decades near Palmer Station, wester nAntarctic Peninsula, have 
provided additional support for this hypothesis, suggesting 
that "habitat-specific demography" (see Pulliam 1988; 1996) may be 
an important but unrecognized feature in the population dynamics of 
Adelie penguins. Although the causal mechanisms involved are still 
under investigation, preliminary findings indicate that the relevant 
processes are linked to interactions between breeding habitat 
geomorphology and changing patterns of snow deposition due to 
climate warming. One result of these processes is a form of 
habitat fragmentation, which in turn affects demography at multiple 
space (individuals, colonies, rookeries) and time (interannual to 
centuries) scales. These findings further imply that theexisting 
information base needed to understand and model Ad=E9lie 
penguin population dynamics may be incomplete unless the potential 
effects of breeding habitat variability on demography are
recognized. Because the species is regarded as a bio- indicator, 
this could impair the interpretation of data related to the 
effects of climate change, fisheries and human disturbance in
Antarctica. 

Fraser W. R, Patterson D. L. 1997. Antarctic
Communities, Species, Structure and Survival, Proc. VI SCAR Biol.
Symp., Cambridge University Press, 445-452. 

Fraser W.R., Trivelpiece W.Z, Ainley D.G., Trivelpiece, S.G. 
1992. Pol. Biol. 11: 525- 531.

Pulliam H.R. 1988. Am. Nat. 132, 654-661.

Pulliam H.R. 1996. Population Dynamics in Ecological Space and 
Time, University of Chicago Press, 45-69.

Trivelpiece W. Z., Trivelpiece S. G., Geupel G.R., Kjelmyr 
J., & Volkman N.J. 1990 Antarctic Ecosystems, Ecological 
Change and Conservation, Proc. V SCAR Biol. Symp., 
Springer-Verlag, 191-202.