Three neotropical bird species shift nest‐site preferences from swollen‐thorn acacias to other sites in human‐altered habitats

Abstract

AbstractNest location is a decision that presumably affects predation probability, thus, it directly impacts offspring survival. Those locations could be near animals that deter potential nest predators, like acacia ants. We tested whether the preference of three neotropical bird species (Icterus pustulatus, Tolmomyias sulphurescens and Pitangus sulphuratus) for nesting in swollen‐thorn acacias (Vachellia) shifted in human‐modified landscapes. Because natural predators deterred by ant‐defended acacias in protected forest may decrease or be replaced by other predators in human‐modified landscapes, we predicted a potential loss of preference for swollen‐thorn acacias in those landscapes. Swollen‐thorn acacias can be inhabited by defending Pseudomyrmex ants (ant‐defended acacias) or by non‐defending ants (non‐defended acacias). Hence, a preference for nesting on ant‐defended acacias was expected in natural habitats but not in anthropogenic habitats. All three bird species preferred to nest in swollen‐thorn acacias in forests, but only P. sulphuratus showed a preference for ant‐defended acacias. However, this nesting preference of all three species was lost in human‐modified landscapes, where birds switched to large trees, and included utility poles or power lines, although acacias remained a common species. The preference of P. sulphuratus for ant‐defended acacias in the forests was also lost in anthropic areas. The habitat‐dependent shift in preference for nesting trees indicates a potential change in the benefits of tree traits and the selective forces (e.g., predators) at those sites. Our results demonstrate that birds who seem strongly dependent on a tree when studied in natural habitats may shift their preferences in altered habitats.Abstract in Spanish is available with online material.