Projecting population responses to climate change requires an understanding of climatic impacts on key components of reproduction. Here, we investigate the associations among breeding phenology, climate and incubation schedules in the chestnut‐crowned babbler (Pomatostomus ruficeps), a 50 g passerine with female‐only, intermittent incubation that typically breeds from late winter (July) to early summer (November). During daylight hours, breeding females spent an average of 33 min on the nest incubating (hereafter on‐bouts) followed by 24‐min foraging (hereafter off‐bouts), leading to an average daytime nest attentiveness of 60%. Nest attentiveness was 25% shorter than expected from allometric calculations, largely because off‐bout durations were double the expected value for a species with 16 g clutches (4 eggs × 4 g/egg). On‐bout durations and daily attentiveness were both negatively related to ambient temperature, presumably because increasing temperatures allowed more time to be allocated to foraging with reduced detriment to egg cooling. By contrast, on‐bout durations were positively associated with wind speed, in this case because increasing wind speed exacerbated egg cooling during off‐bouts. Despite an average temperature change of 12°C across the breeding season, breeding phenology had no effect on incubation schedules. This surprising result arose because of a positive relationship between temperature and wind speed across the breeding season: Any benefit of increasing temperatures was canceled by apparently detrimental consequences of increasing wind speed on egg cooling. Our results indicate that a greater appreciation for the associations among climatic variables and their independent effects on reproductive investment are necessary to understand the effects of changing climates on breeding phenology.

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Ducks have developed a variety of foraging strategies that utilize touch sensitive bills to match their ecological niche within wetlands. These techniques include diving, sieving, dabbling, and grazing. Ducks exhibiting tactile specialization in foraging outperform visual and non-tactile foraging ducks in behavioral experiments and have a higher percentage of light-touch mechanoreceptor neurons expressing Piezo2 in the trigeminal ganglia. Belonging to two different tribes of Anseriformes, the well-studied tactile specialist Pekin (Tribe Anatini: Anas platyrhynchos domestica) and lesser studied Muscovy (Tribe Cairinini: Cairina moschata domestica) ducks were tested on a series of experiments to assess these birds’ functional tactile acuity. Both species of duck were able to separate out and consume edible items from increasing amounts of inedible plastiline clay distractors. They could also both be trained to associate a food reward with plastiline stimuli of differing size and shape using touch alone. However, only females of each species could learn to associate food reward with otherwise identical stimuli differing only in hardness. Pekin females performed significantly better than Muscovy females suggesting the anatomical specializations present in many Anatini may contribute to this type of tactile acuity. These findings have potential relevance in understanding the evolution of tactile ability and feeding ecology.

Phenotypic plasticity is hypothesized to facilitate adaptive responses to challenging conditions, such as those resulting from climate change. However, tests of the key predictions of this ‘rescue hypothesis’, that variation in plasticity exists and can evolve to buffer unfavourable conditions, remain rare. Here, we investigate among‐female variation in temperature‐mediated plasticity of incubation schedules and consequences for egg temperatures using the chestnut‐crowned babbler (Pomatostomus ruficeps) from temperate regions of inland south‐eastern Australia. Given recent phenological advances in this seasonal breeder and thermal requirements of developing embryos (>~25°C, optimally ~38°C), support for evolutionary rescue—perhaps paradoxically—requires that plasticity serves to buffer embryos more from sub‐optimally low temperatures. We found significant variation in the duration of incubation bouts (mean ± SD = 27 ± 22 min) and foraging bouts (mean ± SD = 17 ± 11 min) in this maternal‐only incubator. However, variation in each arose because of variation in the extent to which mothers increased on‐ and off‐bout durations when temperatures (0–36°C) were more favourable rather than unfavourable as required under rescue. In addition, there was a strong positive intercept‐slope correlation in on‐bout durations, indicating that those with stronger plastic responses incubated more at average temperatures (~19°C). Combined, these effects reduced the functional significance of plastic responses: an individual's plasticity was neither associated with daily contributions to incubation (i.e. attentiveness) nor average egg temperatures. Our results highlight that despite significant among‐individual variation in environmental‐sensitivity, plasticity in parental care traits need not evolve to facilitate buffering against unfavourable conditions.