How Does Temperature Affect Nest Success of Eastern Bluebirds?
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Authors
Brow, Morgan
Mockerman, Regan
Spear, Emily
Wortley, Sarah
Issue Date
2025-04-03
Type
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Keywords
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Abstract
Description
As global temperatures continue to rise, avian species face many challenges, especially during
the summer breeding months. Higher temperatures are negatively correlated with nest success,
because of the direct effect they have on reproductive behaviors and metabolism. When breeding
birds return to the same geographical region every year, they become physiologically adapted to
such conditions. However, it is unclear whether these adaptations will remain beneficial as
temperatures change. Our overall research question is: how does temperature affect breeding
biology and fitness of birds. Specifically, we will examine how temperature effects clutch size,
hatching success, fledging success, and nestling growth and development. Eastern Bluebirds are
secondary cavity nesting birds that are found in central Michigan and readily use human constructed nest boxes. We have three sites near Alma, MI, with 50 nest boxes total. We
experimentally manipulated the internal temperature of active nest boxes via heating packs, ice
packs, and no alterations as a control. We placed a temperature datalogger into each active nest
box that records temperature every hour. We will visit nest boxes every 1-4 days, recording
clutch size, number of nestlings, and nesting size starting in mid-March and throughout the
breeding season. In warm climates, cool nest boxes are more successful, but if bluebirds in
Michigan are physiologically adapted to a cooler environment, we expect the opposite
relationship. Therefore, we expect that experimentally warmed nest boxes will be more
successful than the control or the cooled nest boxes because warm nests will limit the metabolic
demands on the attending female. By determining exactly how temperature affects breeding
biology of Eastern bluebirds in central Michigan, we will be better equipped to make
recommendations that will optimize success while bluebirds adapt to rising temperatures