Communication using chemical cues is important for many taxa, including birds, but the use of olfaction for intraspecific communication has been investigated only recently in passerines and is understudied in nestlings. To address this knowledge gap, we explored whether nestling tree swallows (Tachycineta bicolor) would recognize and respond to chemical cues of conspecifics, specifically testing begging responses to familiar and unfamiliar nest and adult odours. For the nest odour experiment, nests were treated with either orange essential oil or distilled water to create scented and unscented (control) odour environments, respectively. For the adult odour experiment, adults attending the nestlings were considered “familiar adults” and adults attending a different brood in the population were considered “unfamiliar adults.” We found that begging responses of nestlings did not differ in response to orange oil odour or water, but nestlings begged significantly longer and more intensely in response to odours of a familiar than an unfamiliar adult, regardless of adult sex. This provides evidence that tree swallows use chemical cues to alter their behaviour and opens up many exciting avenues of future research.

中文翻译：

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雏树燕子 ( Tachycineta bicolor ) 会根据熟悉的成年人的气味改变乞讨行为，但不会改变它们的巢穴

使用化学线索进行交流对于包括鸟类在内的许多分类群很重要，但最近才在雀鸟中研究了使用嗅觉进行种内交流，而在雏鸟中研究不足。为了解决这一知识差距，我们探索了雏树燕子 (Tachycineta bicolor) 是否会识别和响应同种的化学线索，特别是测试对熟悉和不熟悉的巢穴和成年气味的乞求反应。在蜂巢气味实验中，蜂巢分别用橙色精油或蒸馏水处理，以创造有香味和无香味（对照）的气味环境。对于成年气味实验，参加雏鸟的成年人被认为是“熟悉的成年人”，而参加群体中不同育雏的成年人被认为是“不熟悉的成年人”。”我们发现雏鸟的乞求反应在对橙油气味或水的反应方面没有差异，但与不熟悉的成年人相比，雏鸟对熟悉的气味的乞求时间明显更长，更强烈，无论成年性别如何。这提供了证据表明树燕使用化学线索来改变它们的行为，并为未来的研究开辟了许多令人兴奋的途径。