Short-term, but not long-term, increased daytime workload leads to decreased night-time energetics in a free-living song bird.
J Exp Biol
; 222(Pt 14)2019 07 19.
Article
em En
| MEDLINE
| ID: mdl-31278130
ABSTRACT
Reproduction is energetically expensive and to obtain sufficient energy, animals can either alter their metabolic system over time to increase energy intake (increased-intake hypothesis) or reallocate energy from maintenance processes (compensation hypothesis). The first hypothesis predicts a positive relationship between basal metabolic rate (BMR) and energy expenditure (DEE) because of the higher energy demands of the metabolic system at rest. The second hypothesis predicts a trade-off between different body functions, with a reduction of the BMR as a way to compensate for increased daytime energetic expenditure. We experimentally manipulated the workload of wild pied flycatchers by adding or removing chicks when chicks were 2 and 11â
days old. We then measured the feeding frequency (FF), DEE and BMR at day 11, allowing us to assess both short- and long-term effects of increased workload. The manipulation at day 2 caused an increase in FF when broods were enlarged, but no response in DEE or BMR, while the manipulation at day 11 caused an increase in FF, no change in DEE and a decrease in BMR in birds with more chicks. Our results suggest that pied flycatchers adjust their workload but that this does not lead to a higher BMR at night (no support for the increased-intake hypothesis). In the short term, we found that birds reallocate energy with a consequent reduction of BMR (evidence for the compensation hypothesis). Birds thus resort to short-term strategies to increase energy expenditure, which could explain why energy expenditure and hard work are not always correlated in birds.
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01-internacional
Base de dados:
MEDLINE
Assunto principal:
Reprodução
/
Ingestão de Energia
/
Aves Canoras
/
Metabolismo Energético
Limite:
Animals
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article