| | |
Summary: Abstract Blue-footed boobies (Sula nebouxii) in the
Galápagos Islands nest at coastal sites such as cliff edges
if Nazca boobies (S. granti) are absent. However, if
sympatric with nesting Nazca boobies, they nest nearby,
but farther inland, in areas with little topographical relief.
Nazca boobies nest at the coastal sites whether blue-foot-
ed boobies are present or not. The segregated nesting pat-
tern of these two species offers a model system to investi-
gate factors influencing community structure. We tested a
non-interactive hypothesis, in which different fundamen-
tal niches generate the non-overlapping distributions, and
an interactive hypothesis, in which the two fundamental
niches overlap and an interaction between the two species
causes the segregation. Data on three factors considered
as likely parameters differentiating fundamental niches
(nest microclimate, nature of the nesting substrate, and
ease of taking flight from nest sites) failed to support the
non-interactive hypothesis. These results suggest that the
two species have indistinguishable fundamental niches
with respect to these parameters, but different realized
|
