Extended incubation recesses by alpine-breeding Horned Larks: a strategy for dealing with inclement weather?

Abstract

Incubating birds can incur high energetic costs and, when faced with a trade‐off between incubation and foraging, parents may neglect their eggs in favor of their own somatic needs. Extended incubation recesses are an example of neglect, but they are often treated as outliers and largely overlooked in studies of incubation behavior. We studied incubation rhythms of Horned Larks (Eremophila alpestris) on Hudson Bay Mountain, British Columbia, Canada, during four breeding seasons. Incubation recesses averaged 10.92 ± 0.38 min (N= 4076 2‐h periods), but we observed 70 extended recesses, ranging from 59 to 387 min in duration, at 35 nests. Although rare (<1% of all daytime recesses), extended recesses occurred in all 4 yr, were longer and more frequent in colder years (60% occurred in the two coldest years), and often occurred during inclement weather (39% occurred during three storm events). Extended recesses did not appear to compensate for long attendance periods because extended recess duration was not correlated with the duration of previous on‐bouts (P= 0.10, N= 70) or the mean on‐bout duration of the previous 2‐h period (P= 0.36, N= 70). Rather, extended recesses seemed to reflect a shift in parental investment away from their eggs and toward self‐maintenance when faced with energetically stressful conditions. Extended recesses may have reduced embryo viability; egg‐hatching rates were 91 ± 2.4% for nests where females did not take extended recesses and 81 ± 4.2% for nests where females did take extended recesses (P= 0.02, N= 56 nests). Extended recesses during incubation are rare events, but they may represent an important mechanism that allows birds to breed successfully in energetically challenging conditions.

Unusual incubation behavior and embryonic tolerance of hypothermia in the Sichuan Partridge (Arborophila rufipectus)

“…We found that the Sichuan Partridge tended to nest near to trails (see ''Results''), therefore we speculated that human activity might be an important factor influencing its incubation behavior (Verhulst et al 2001;Arroyo and Razin 2006). In addition, inclement weather has been suggested as an important mechanism explaining extended incubation recesses (MacDonald et al 2013). The aims of this study were to: 1.…”

Effects of severe weather on reproduction for sympatric songbirds in an alpine environment: Interactions of climate extremes influence nesting success

“…The timing of snowmelt varies annually, with patches of snow persisting through most of June, and the overall length of the growing season is considerably reduced in comparison to low-elevation habitats used by these species (Camfield et al 2010, MacDonald et al 2014. Daily breeding-season temperatures fluctuate widely at the site, dropping near or below freezing on most nights and sometimes exceeding 408C at ground level during the day , MacDonald et al 2013, 2014. Strong winds and storms involving snow or rain occur throughout the nesting period, with more frequent and extreme events earlier in the breeding season (Figure 1).…”

An alpine-breeding songbird can adjust dawn incubation rhythms to annual thermal regimes

“…The timing of snowmelt varies annually, with patches of snow persisting through most of June, and the overall length of the growing season is considerably reduced in comparison to low-elevation habitats used by these species (Camfield et al 2010. Daily breeding-season temperatures fluctuate widely at the site, dropping near or below freezing on most nights and sometimes exceeding 408C at ground level during the day , MacDonald et al 2013, 2014. Strong winds and storms involving snow or rain occur throughout the nesting period, with more frequent and extreme events earlier in the breeding season (Figure 1).…”