Incubation Temperature Affects Growth and Energy Metabolism in Blue Tit Nestlings

Abstract

Because the maintenance of proper developmental temperatures during avian incubation is costly to parents, embryos of many species experience pronounced variation in incubation temperature. However, the effects of such temperature variation on nestling development remain relatively unexplored. To investigate this, we artificially incubated wild blue tit (Cyanistes caeruleus L.) clutches at 35.0°, 36.5°, or 38.0°C for two-thirds of the incubation period. We returned clutches to their original nests before hatching and subsequently recorded nestling growth and resting metabolic rate. The length of the incubation period decreased with temperature, whereas hatching success increased. Nestlings from the lowest incubation temperature group had shorter tarsus lengths at 2 weeks of age, but body mass and wing length were not affected by temperature. In addition, nestlings from the lowest temperature group had a significantly higher resting metabolic rate compared with mid- and high-temperature nestlings, which may partly explain observed size differences between the groups. These findings suggest that nest microclimate can influence nestling phenotype, but whether observed differences carry over to later life-history stages remains unknown.

Transient and permanent effects of suboptimal incubation temperatures on growth, metabolic rate, immune function, and adrenocortical responses in zebra finches

“…In altricial birds, a lower than optimal incubation temperature increases metabolic rates during embryonic development as well as in the nestling period (Olson et al, 2006;Nord and Nilsson, 2011). We observed that female fledglings from the 36.2°C group had a relatively high BMR compared with fledglings hatched from 37.4°C.…”

“…Previous studies show that incubation temperature affects metabolic rates and the hypothalamic-pituitary-adrenal (HPA) axis function in birds for the first 2 weeks of life (DuRant et al, 2010;Nord and Nilsson, 2011): altricial blue tit (Cyanistes caeruleus) nestlings that hatched from eggs incubated at 35.0°C had significantly higher resting metabolic rates at ∼14 days post-hatch (dph; hatch day is 0 dph) compared with nestlings hatched from eggs incubated at 36.5 or 38.0°C (Nord and Nilsson, 2011). Similarly, precocial wood duck (Aix sponsa) embryos that were incubated at 35.0°C expended significantly more energy during the hatching process compared with embryos incubated at 35.9 or 37.0°C (DuRant et al, 2011).…”

Brood size constrains the development of endothermy in blue tits

“…The air inside the chamber was still, but the large internal volume of the cooler (5500 cm 3 ) relative to the size and oxygen consumption of blue tit nestlings, ca. 1.5 ml O 2 min −1 at day 14 (Nord and Nilsson, 2011), should make the risk of hypoxia highly unlikely. We measured skin temperature (T sk ) on a single spot on the abdomen of the nestlings at the start (T s ) and end (T f ) of a cooling session (i.e.…”

Progression in the bacterial load during the breeding season in nest boxes occupied by the Blue Tit and its potential impact on hatching or fledging success

“…have been found to be prevalent (Sanders et al 2005). Upon incubation, the temperature of the nest cup and the eggs rises to between 35 and 38 °C (Nord and Nilsson 2011); this temperature range is closely related to the body temperature of the adult birds and as such the optimum temperature for hostassociated bacteria. These findings lead to the expectation that the bacterial load would increase significantly with this increase in ambient temperature compared with the bacterial load at the earlier ambient temperature.…”

“…This result was somewhat unexpected. One possible explanation is based on the removal of belly feathers by the female prior to incubation to aid in efficient temperature transfer to the eggs (Nord and Nilsson 2011). These feathers are then used as lining material in the nest cup.…”