Elevation and forest clearing effects on foraging differ between surface--and subterranean--foraging army ants...

Area of Science:

• Ecology
• Entomology
• Conservation Biology

Background:

• Forest fragmentation creates habitat mosaics, impacting large-ranging predators like army ants (Formicidae: Ecitoninae).
• Lowland forest clearing negatively affects army ant foraging and population persistence, potentially due to high temperatures hindering above-ground activity.

Purpose of the Study:

• To investigate how elevation and foraging strategy (above-ground vs. subterranean) influence army ant responses to forest clearing.
• To determine if higher elevations in montane forests reduce the negative impacts of open areas on army ant foraging.
• To assess if subterranean foraging provides a buffer against habitat modification effects.

Main Methods:

• Quantified foraging rates of above-ground and underground army ants across an elevational gradient (1090–1540 m).
• Compared foraging rates in open matrix areas versus forested habitats at matched elevations.
• Monitored ground surface temperatures in open and forested areas to correlate with foraging activity.

Main Results:

• Above-ground army ant foraging rates were lower in open areas, with this difference decreasing at higher elevations.
• Underground foraging rates were unaffected by habitat type but increased with elevation.
• Higher ground surface temperatures in open areas, which decreased with elevation, explained the observed foraging patterns.

Conclusions:

• Above-ground army ant foraging is constrained by thermal tolerance in open areas, a limitation lessened at higher, cooler elevations.
• Subterranean foraging allows some army ant species to maintain foraging success in modified landscapes.
• Findings highlight the importance of elevation and foraging strategy in army ant adaptation to habitat modification and climate change.