Extreme and variable torpor among high-elevation Andean hummingbird species

Title
Extreme and variable torpor among high-elevation Andean hummingbird species
Publication Date
2020-09
Author(s)
Wolf, Blair O
McKechnie, Andrew E
Schmitt, C Jonathan
Czenze, Zenon J
( author )
OrcID: https://orcid.org/0000-0002-1113-7593
Email: zczenze@une.edu.au
UNE Id une-id:zczenze
Johnson, Andrew B
Witt, Christopher C
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
The Royal Society Publishing
Place of publication
United Kingdom
DOI
10.1098/rsbl.2020.0428
UNE publication id
une:1959.11/61219
Abstract

Torpor is thought to be particularly important for small endotherms occupying cold environments and with limited fat reserves to fuel metabolism, yet among birds deep torpor is both rare and variable in extent. We investigated torpor in hummingbirds at approximately 3800 m.a.s.l. in the tropical Andes by monitoring body temperature (Tb) in 26 individuals of six species held captive overnight and experiencing natural air temperature (Ta) patterns. All species used pronounced torpor, with one Metallura phoebe reaching a minimum Tb of 3.26°C, the lowest yet reported for any bird or non-hibernating mammal. The extent and duration of torpor varied among species, with overnight body mass (Mb) loss negatively correlated with both minimum Tb and bout duration. We found a significant phylogenetic signal for minimum Tb and overnight Mb loss, consistent with evolutionarily conserved thermoregulatory traits. Our findings suggest deep torpor is routine for high Andean hummingbirds, but evolved species differences affect its depth.

Link
Citation
Biology Letters, 16(9), p. 1-5
ISSN
1744-957X
1744-9561
Pubmed ID
32898456
Start page
1
End page
5

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