Differences in begging behaviour between barn swallow, Hirundo rustica, nestlings

Area of Science:

• Animal Behavior
• Evolutionary Biology
• Ornithology

Background:

• Parent-offspring communication models propose nestling begging signals food needs.
• Nestling need is influenced by immediate hunger and long-term factors like size and condition.

Purpose of the Study:

• To investigate how nestling begging behavior reflects short- and long-term needs in barn swallows.
• To determine if brood size manipulation affects nestling growth, body condition, and subsequent begging strategies.

Main Methods:

• Barn swallow brood sizes were manipulated to create varying growth rates and body conditions.
• Nestling begging was measured in controlled laboratory tests, assessing temporal hunger variations.
• Four target nestlings (small/large, from small/large broods) were tested simultaneously.

Main Results:

• Small nestlings and those from large broods exhibited lower growth rates and poorer body condition.
• Begging behavior positively correlated with both short-term hunger and long-term need indicators.
• Begging trends became mixed with age, with the neediest nestlings (small, large broods) reducing begging.

Conclusions:

• Nestling begging strategies are influenced by brood size and individual rank.
• Variations in begging may reflect long-term need, past experiences, or perceived costs/benefits of begging.