Results of Common Loon territory monitoring (1979–2009) and of chick monitoring surveys (2004–2006) at Voyageurs National Park

Recovering species are not returning to the same environments or
communities from which they disappeared. Conservation researchers and
practitioners are thus faced with additional challenges in ensuring
species resilience in these rapidly changing ecosystems. Assessing the
resilience of species in these novel systems can still be guided by
species’ ecology, including knowledge of their population size, life
history traits, and behavioral adaptations, as well as the type, strength,
and number of ways that they interact with other species in the community.
We summarized broad trends of Common Loons (Gavia immer) breeding at
Voyageurs National Park during 1973–2009 and evaluated the effects of
increased risk from recovering Bald Eagles (Haliaeetus leucocephalus) on
chick survival during 2004–2006. Adult Common Loons appear to have
increased over time. Using Bayesian survival models that accounted for
imperfect detection of unmarked individuals, we determined that chick
survival of Common Loons was high from year to year and was unrelated to
predation risk from Bald Eagles as chicks in territories closer to active
nests did not experience greater mortality than those further away. We
suggest that Common Loon chicks were unaffected by the recovery of this
top predator during the three years of sampling. Previous research
indicates that Bald Eagles and other predators are an important source of
egg losses, but Common Loons can compensate by re–nesting. Despite current
uncertainties from anthropogenic threats, knowledge of a species’ ecology
remains instrumental in determining their resilience during
recovery.