Data from: Biparentally incubating Aegithalos concinnus (Black-throated Tit) provide a more stable nest thermal environment than uniparentally incubating A. glaucogularis (Silver-throated Tit)

Different parental care modes in birds have been thought to be adaptations
to different environmental conditions, but their adaptability to
environments remains underexplored. We predict that the biparentally
incubating species have a better adaptability to environments than the
uniparentally incubating species. By comparing two congenic species (the
uniparentally incubating Silver-throated Tits Aegithalos glaucogularis and
the biparentally incubating Black-throated Tits A. concinnus) from their
sympatric populations in central China, we found that Silver-throated Tits
had shorter on- and off-bouts (i.e., shorter time on and off the nest)
than Black-throated Tits. When ambient temperature increased, both species
decreased on-bout duration and increased off-bout duration, but the
decrease of on-bout duration in Black-throated Tits was to a greater
degree. Moreover, only Black-throated Tits extended off-bouts after longer
on-bouts, although both species extended on-bout durations after longer
off-bouts. In addition, when ambient temperature increased, their daytime
cumulative nest temperatures increased, whereas nest temperature
fluctuations decreased. However, despite that their daytime cumulative
nest temperatures were similar, Silver-throated Tit nests experienced more
temperature fluctuations. These patterns imply that biparentally
incubating Black-throated Tits have more flexible strategies in egg care
and a better ability to maintain a stable nest thermal environment than
uniparentally incubating Silver-throated Tits. The findings highlight
different adaptive potentials between biparentally and uniparentally
incubating birds, shedding light on the evolution of different incubation
modes in birds.

学界普遍认为，鸟类不同的亲代抚育模式是对不同环境条件的适应性演化，但这些模式对环境的适应潜力仍有待深入探索。本研究推测，双亲孵卵物种对环境的适应能力优于单亲孵卵物种。本研究以中国中部同域分布的两种近缘长尾山雀为研究对象：单亲孵卵的银喉长尾山雀（Aegithalos glaucogularis）与双亲孵卵的黑喉长尾山雀（A. concinnus），对比后发现，银喉长尾山雀的巢内停留时长（on-bout）与离巢时长（off-bout）均短于黑喉长尾山雀。随着环境温度升高，两种山雀均缩短了巢内停留时长，延长了离巢时长，但黑喉长尾山雀的巢内停留时长缩短幅度更大。此外，尽管两种山雀在离巢时长增加后均会延长巢内停留时长，但仅黑喉长尾山雀会在巢内停留时长增加后延长离巢时长。随着环境温度升高，两种山雀的日间巢内累计温度均有所上升，而巢内温度波动则有所降低。不过，尽管两种山雀的日间巢内累计温度相近，但银喉长尾山雀的巢内温度波动幅度更大。上述结果表明，相较于单亲孵卵的银喉长尾山雀，双亲孵卵的黑喉长尾山雀在卵育护方面拥有更灵活的策略，且更能够维持稳定的巢内热环境。本研究结果揭示了双亲孵卵与单亲孵卵鸟类之间不同的适应潜力，为鸟类不同孵卵模式的演化提供了新的科学视角。