The Wilson Journal of Ornithology 123(2):266~276, 2011 
ARCTIC FOXES, LEMMINGS, AND CANADA GOOSE NEST 
SURVIVAL AT CAPE CHURCHILL, MANITOBA 
MATTHEW E. REITER 134 AND DAVID E. ANDERSEN 2 
ABSTRACT.—We examined factors influencing Canada Goose (Branta canadensis interior) annual nest success, 
including the relative abundance of collared lemmings {Dicrostonyx richardsoni ). arctic fox (Alopex lagopus) den 
occupancy, nest density, and spring phenology using data collected during annual Canada Goose breeding area surveys ai 
Cape Churchill, Manitoba. Nest density and arctic fox den occupancy strongly influenced Canada Goose nest success. High 
nest density resulted in higher nest success and high den occupancy reduced nest success. Nest success was not influenced 
by lemming abundance in the current or previous year as predicted hy the 1 ‘bird-lemming” hypothesis. Reducing arctic fro 
abundance through targeted management increased nest survival of Canada Geese; a result that further emphasis the 
importance of arcUc fox as nest predators m this system. The spatial distribution of nest predators, at least for dispersed- 
nestmg geese, may be most important for nest survival, regardless of the abundance of small mammals in the local 
ecosystem. Further understanding of the factors influencing the magnitude and variance in arctic fox abundance in this 
dv^mirr/n m spat '? at lhese fac,ors arc realized, is necessary to fully explain predator-prey-altemative prey 
dynamics in this system. Received 22 June 2010. Accepted 5 January 2011. 
Substantial inter-annuaJ variation occurs in 
reproductive parameters of many arctic and sub¬ 
arctic nesting geese (Bruggink et at. 1994, 
Gleason et al. 2004). Factors influencing this 
variation include annual weather fluctuations 
(Ryder 1970. Raveling and Lumsden 1977, Reiter 
2009) and changes in predator pressure (Angel- 
stam et al. 1984, Summers 1986, Bety et al. 2001). 
Late onset ot snow melt and spring phenology 
directly affects condition of female geese result¬ 
ing in low nest densities and increased nest failure 
(Ryder 1970, Moser and Rusch 1998). Variation 
in nest success from changes in predator pressure 
is likely more complex and often involves the 
dynamic interaction of potential nest predators 
with their primary and alternative prey (Angel- 
stam et al. 1984, Summers 1986). Understanding 
these inter-specific associations in a predator-prey 
system requires consideration of the spatial scale 
at which inter-specific interactions occur. 
The alternative-prey hypothesis refers to pred¬ 
ator-prey relationships where predators specialize 
on primary prey until that prey population 
declines below a threshold density, at which point 
they functionally respond and consume alternative 
Minnesota Cooperative Fish and Wildlife Research 
Unit, Department of Fisheries, Wildlife, and Conservation 
Biology, University of Minnesota. 200 Hodson Hall 1980 
Folwell Avenue. St. Haul, MN 55108, USA. 
SurVey ’ Minnesota Cooperative Fish 
and Wildlife Research Unit. 200 Hodson Hall, 1980 Folwell 
Avenue, St. Paul, MN 55108, USA 
F ie 3 ,?™ d PRB ? Co "«™»ion Science, TomKa. 
Station. P. O. Box 747, Pcscadero, CA 94060. USA 
Corresponding author; e-mail: mreiter@prbo.org 
prey (Angclstam et al. 1984). This behavior 
typically occurs when the predator is specialized 
and experiences reduced fitness with declining 
primary prey. However, the form of the functional 
response of the predator to changes in abundance 
of primary and secondary prey may vary depend¬ 
ing on the spatial distribution and abundance of 
the alternative prey resource, as well as the 
relative cost of migrating in search of alternative 
food concentrations (Angerbjbm et al. 1999). 
Annual variation in nest success of arctic- 
nesting birds and the relationship with small 
mammals (“bird-lemming” hypothesis) has been 
recognized in northern Russia and Europe (An- 
gelstam ct al. 1984, Summers 1986) and in North 
America (Wilson and Bromley 2001; Bety et al. 
2001, 2002). Arctic fox (Alopex lagopus ) and 
other predators specialize in feeding on primary 
prey, lemmings (Dicrostonyx spp.. Lernmus spp.). 
under the apparent-competition theory of this 
hypothesis and increase reproduction when lem¬ 
mings are abundant. Predators switch to feeding 
on alternative prey including ground-nesting birds 
and bird eggs in years when lemming abundance 
is low. Subsequently, ground-nesting birds arc 
predicted to experience reduced reproductive 
performance in the year following a lemming 
peak when arctic fox are abundant, but likely 
recover in subsequent years as predator popula¬ 
tions decline (Angelslam et al. 1984, Summers 
1986). This theoretical hypothesis has been 
corroborated with some empirical data from large 
colonies of arctic-nesting birds (e.g., Bety et al. 
2002), but few studies have assessed the bird¬ 
lemming hypothesis in relation to dispersed- 
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