Prey Availability for Tree Swallows Tachycineta bicolor in Four Lentic Wetlands: Resistance to Phenological Mismatch for the Year 2020

During the reproductive season, Tree Swallows (Tachycineta bicolor) are found at higher latitudes in 
North America along many bodies of water during the breeding season. These aerial avian 
insectivores feed their young insects they catch on the wing.Tree Swallow proximity to bodies of 
water infers that these birds may rely on aquatic emergent insects to feed their young. Emergent 
insects are often higher in omega-3 fatty
acids compared to terrestrially derived insects. Omega-3 fatty acids are essential to support chick 
growth and immune resistance. To gain a better understanding of Tree Swallow trophic dynamics, it is 
important to study the importance of terrestrial and emergent insect abundance to the timing of Tree 
Swallow reproduction. In the present study, I examined five small lentic wetlands in central 
Pennsylvania for insect availability and Tree Swallow reproductive events. I used emergent insect 
traps as well as terrestrial sweep netting to sample the local environment and found that breeding 
events are coupled strongly with the availability of different classes of insects, primarily dipterans. 
Climate change stands to disrupt that relationship through phenological mismatches,
where insects emerge earlier than the Tree Swallow reproductive events anticipate. My study found 
that Tree Swallow reproduction more closely aligned with sweep netted dipterans not emergent 
insect abundances. This suggests that Tree Swallows may be resistant to potential phenological 
mismatches caused by climate change.