Breeding biology of two populations of Chinese penduline tits

The phenotypes and breeding behavior in one species may be different
between populations. The local environments, social interactions can all
lead to some variations in life history. The thorough investigations of
breeding biology over populations can provide insights for us to
understand the evolution and diversifications of breeding systems and
phenotypic traits from multiple perspectives other than drawing monotonous
associations between a factor and a trait. In this study, we explored two
Chinese penduline populations, Liaohekou (LHK) and Xianghai (XH), both in
the northeast of China located 550 km away from each other. A comparative
study of the breeding biology was carried on in the two populations. We
found that the climate has no obvious difference in these two populations
but has different habitats. Nest emergence and egg-laying were earlier in
the more northern population XH. Males in XH has a lower chance of pairing
up with a female and exhibit mainly biparental care pattern instead
uniparental care that we reported in LHK. The chick fledgling success in
the biparental care nests was higher than in the uniparental care nests in
XH, but no difference to the uniparental care nests in LHK. Besides, the
penduline tits in the two populations were also significantly different in
their wing length, tail length and beak shape. These incongruences
suggested different food availability, adult sex ratio and migration
distances of the two populations. Future studies should experimentally
investigate the joint influences of breeding perspectives on the evolution
of parental care and mating system.