Seasonal changes in plumage density, plumage mass, and feather morphology in the world’s northernmost land bird, the Svalbard Rock Ptarmigan (Lagopus muta hyperborea)

Nord, Andreas; Holje, Vidar; Judik, Benjamin; Folkow, Lars P.; Pap, Péter L

Seasonal changes in plumage density, plumage mass, and feather morphology in the world’s northernmost land bird, the Svalbard Rock Ptarmigan (Lagopus muta hyperborea)

Mark

Nord, Andreas ^LU ; Holje, Vidar ; Judik, Benjamin ; Folkow, Lars P. and Pap, Péter L (2023) In Polar Biology 46(4). p.277-290

Abstract: The Svalbard Rock Ptarmigan, Lagopus muta hyperborea, is the only year-round resident terrestrial bird in the high Arctic. Many of the physiological and morphological adaptations permitting its winter endurance in this harsh environment are well understood. However, it remains unknown how the conspicuous moult from a greyish brown summer to a white winter plumage, and any underlying changes in plumage structure and feather morphology, contribute to seasonal acclimatisation. We used standard morphometric techniques to describe the seasonal change in plumage and feather characteristics in six body regions. Then, we investigated whether winter plumage traits differed between first-winter and adult (second winter, or older) birds, because a... (More); The Svalbard Rock Ptarmigan, Lagopus muta hyperborea, is the only year-round resident terrestrial bird in the high Arctic. Many of the physiological and morphological adaptations permitting its winter endurance in this harsh environment are well understood. However, it remains unknown how the conspicuous moult from a greyish brown summer to a white winter plumage, and any underlying changes in plumage structure and feather morphology, contribute to seasonal acclimatisation. We used standard morphometric techniques to describe the seasonal change in plumage and feather characteristics in six body regions. Then, we investigated whether winter plumage traits differed between first-winter and adult (second winter, or older) birds, because a difference in coat insulation has been suggested as an explanation for why first-winter Svalbard Ptarmigan loose more heat than adults. Plumage feather density (i.e., feathers × cm−2) and mass density (i.e., mg feathers × cm−2) were higher in winter, particularly on the head and feet where individual feathers were also heavier, longer, and downier. Seasonal changes in other regions (back, tarsi) indicated acclimatisation primarily to resist physical wear and wind. First-winter and adult birds had similar feather densities. However, mass density in first-winter birds was significantly lower than in adults in all but one body region (back) because individual feathers weighed less. This can explain previous observations of higher heat loss rates in first-winter birds. Our study suggests that plumage acclimatisation contributes to optimising the winter phenotype of Svalbard Rock Ptarmigan, both through higher insulative capacity and by improved resistance to harsh weather. The extent of these adaptations may be determined by the time or energy available for feather growth, exemplified here by inferior insulation in first-winter birds. (Less)
Abstract (Swedish): The Svalbard Rock Ptarmigan, Lagopus muta hyperborea, is the only year-round resident terrestrial bird in the high Arctic. Many of the physiological and morphological adaptations permitting its winter endurance in this harsh environment are well understood. However, it remains unknown how the conspicuous moult from a greyish brown summer to a white winter plumage, and any underlying changes in plumage structure and feather morphology, contribute to seasonal acclimatisation. We used standard morphometric techniques to describe the seasonal change in plumage and feather characteristics in six body regions. Then, we investigated whether winter plumage traits differed between first-winter and adult (second winter, or older) birds, because a... (More); The Svalbard Rock Ptarmigan, Lagopus muta hyperborea, is the only year-round resident terrestrial bird in the high Arctic. Many of the physiological and morphological adaptations permitting its winter endurance in this harsh environment are well understood. However, it remains unknown how the conspicuous moult from a greyish brown summer to a white winter plumage, and any underlying changes in plumage structure and feather morphology, contribute to seasonal acclimatisation. We used standard morphometric techniques to describe the seasonal change in plumage and feather characteristics in six body regions. Then, we investigated whether winter plumage traits differed between first-winter and adult (second winter, or older) birds, because a difference in coat insulation has been suggested as an explanation for why first-winter Svalbard Ptarmigan loose more heat than adults. Plumage feather density (i.e., feathers × cm−2) and mass density (i.e., mg feathers × cm−2) were higher in winter, particularly on the head and feet where individual feathers were also heavier, longer, and downier. Seasonal changes in other regions (back, tarsi) indicated acclimatisation primarily to resist physical wear and wind. First-winter and adult birds had similar feather densities. However, mass density in first-winter birds was significantly lower than in adults in all but one body region (back) because individual feathers weighed less. This can explain previous observations of higher heat loss rates in first-winter birds. Our study suggests that plumage acclimatisation contributes to optimising the winter phenotype of Svalbard Rock Ptarmigan, both through higher insulative capacity and by improved resistance to harsh weather. The extent of these adaptations may be determined by the time or energy available for feather growth, exemplified here by inferior insulation in first-winter birds. (Less)

Please use this url to cite or link to this publication: https://lup.lub.lu.se/record/e1a171c9-505b-4066-aae4-765ddd1cea98

author

Nord, Andreas ^LU ; Holje, Vidar ; Judik, Benjamin ; Folkow, Lars P. and Pap, Péter L

organization

publishing date

2023

type

Contribution to journal

publication status

published

subject

Zoology

keywords

Arctic, Polar, Feather, moult, Plumage, Thermoregulation, Bird, polar, arctic, bird, moult, thermoregulation, ptarmigan, season, feather, plumage

in

Polar Biology

volume

46

issue

4

pages

277 - 290

publisher

Springer

external identifiers

scopus:85150599442

ISSN

1432-2056

DOI

10.1007/s00300-023-03118-8

language

English

LU publication?

yes

id

e1a171c9-505b-4066-aae4-765ddd1cea98

date added to LUP

2023-03-25 09:02:08

date last changed

2023-05-29 14:33:44

@article{e1a171c9-505b-4066-aae4-765ddd1cea98,
  abstract     = {{The Svalbard Rock Ptarmigan, Lagopus muta hyperborea, is the only year-round resident terrestrial bird in the high Arctic. Many of the physiological and morphological adaptations permitting its winter endurance in this harsh environment are well understood. However, it remains unknown how the conspicuous moult from a greyish brown summer to a white winter plumage, and any underlying changes in plumage structure and feather morphology, contribute to seasonal acclimatisation. We used standard morphometric techniques to describe the seasonal change in plumage and feather characteristics in six body regions. Then, we investigated whether winter plumage traits differed between first-winter and adult (second winter, or older) birds, because a difference in coat insulation has been suggested as an explanation for why first-winter Svalbard Ptarmigan loose more heat than adults. Plumage feather density (i.e., feathers × cm−2) and mass density (i.e., mg feathers × cm−2) were higher in winter, particularly on the head and feet where individual feathers were also heavier, longer, and downier. Seasonal changes in other regions (back, tarsi) indicated acclimatisation primarily to resist physical wear and wind. First-winter and adult birds had similar feather densities. However, mass density in first-winter birds was significantly lower than in adults in all but one body region (back) because individual feathers weighed less. This can explain previous observations of higher heat loss rates in first-winter birds. Our study suggests that plumage acclimatisation contributes to optimising the winter phenotype of Svalbard Rock Ptarmigan, both through higher insulative capacity and by improved resistance to harsh weather. The extent of these adaptations may be determined by the time or energy available for feather growth, exemplified here by inferior insulation in first-winter birds.}},
  author       = {{Nord, Andreas and Holje, Vidar and Judik, Benjamin and Folkow, Lars P. and Pap, Péter L}},
  issn         = {{1432-2056}},
  keywords     = {{Arctic; Polar; Feather; moult; Plumage; Thermoregulation; Bird; polar; arctic; bird; moult; thermoregulation; ptarmigan; season; feather; plumage}},
  language     = {{eng}},
  number       = {{4}},
  pages        = {{277--290}},
  publisher    = {{Springer}},
  series       = {{Polar Biology}},
  title        = {{Seasonal changes in plumage density, plumage mass, and feather morphology in the world’s northernmost land bird, the Svalbard Rock Ptarmigan (Lagopus muta hyperborea)}},
  url          = {{https://lup.lub.lu.se/search/files/141438932/Nord_et_al._Polar_Biol_2023_Seasonal_changes_in_plumage_density_plumage_mass_and_feather_morphology_in_the_world_s_northernmost_landbird.pdf}},
  doi          = {{10.1007/s00300-023-03118-8}},
  volume       = {{46}},
  year         = {{2023}},
}

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Seasonal changes in plumage density, plumage mass, and feather morphology in the world’s northernmost land bird, the Svalbard Rock Ptarmigan (Lagopus muta hyperborea)