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Interspecific comparison of the flight performance between sparrowhawks and common buzzards migrating at the Falsterbo peninsula: a radar study

Malmiga, Gintaras (2013) BION32 20122
Degree Projects in Biology
Abstract
Abstract

A radar study was performed to compare flight parameters between sparrowhawks and common buzzards during autumn migration at the Falsterbo peninsula, Sweden. Common buzzards had higher flight altitudes and were more selective for wind, yet their air - and cross-country speeds were lower than those of sparrowhawks. Furthermore, common buzzards had higher glide ratio, but lower airspeed while gliding. Moreover, when subdividing birds into two categories of forward and reverse migrants, differences were also observed within the species. Forward migrating sparrowhawks had highest airspeeds, but reverse migrating sparrowhawks had highest groundspeeds. In addition, forward migrating common buzzards had higher groundspeeds than... (More)
Abstract

A radar study was performed to compare flight parameters between sparrowhawks and common buzzards during autumn migration at the Falsterbo peninsula, Sweden. Common buzzards had higher flight altitudes and were more selective for wind, yet their air - and cross-country speeds were lower than those of sparrowhawks. Furthermore, common buzzards had higher glide ratio, but lower airspeed while gliding. Moreover, when subdividing birds into two categories of forward and reverse migrants, differences were also observed within the species. Forward migrating sparrowhawks had highest airspeeds, but reverse migrating sparrowhawks had highest groundspeeds. In addition, forward migrating common buzzards had higher groundspeeds than reverse migrating common buzzards. Forward migrating sparrowhawks and common buzzards had less scattered heading directions, but more scattered track directions than reverse migrants. No difference was observed in forward migrating sparrowhawks and common buzzards’ migratory directions or flight paths in relation to topography. Differences between the species were not only caused by their morphology or flight style preference, but also by environmental factors, such as wind speed and direction and foraging opportunity for sparrowhawks. Results from similar studies are also compared and discussed.

Popular science summary:

Tracking birds with a radar

I have been tracking raptors, common buzzards and sparrowhawks migrating at Falsterbo peninsula, southwestern part of Sweden. This place provides a wonderful opportunity to study bird migration as many birds try to avoid large water barriers and concentrate in places such as Falsterbo with short distance from one coast to another. The aim of the study was to compare flight performance between sparrowhawks and common buzzards by the following parameters: flight altitude and flight speed, performance during soaring/climbing and gliding phases, flight directions, and flight paths over Falsterbo peninsula in relation to topography and wind direction.
The radar provided an opportunity to track an individual bird to a distance of more than 10 km. By measuring the wind speed and direction I could gather information on bird’s speed and direction relative to the air and to the ground, which is the result of the wind effect.
Common buzzards were flying at higher altitudes and were more selective of better winds than sparrowhawks, yet sparrowhawks had higher air-, and cross-country speeds. Moreover, common buzzards had higher glide ratio, but lower sink speed and airspeed while gliding. No significant difference in mean heading and track directions between forward migrating birds was found. In addition no significant difference was found in flight paths in relation to topography.
These results could help evaluate the future effects of climate change on migrating raptors at higher latitudes and the interspecific differences in reaction to the changes.

Supervisor: Thomas Alerstam
Master´s Degree Project in Animal Ecology, 45 credits, 2013
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Malmiga, Gintaras
supervisor
organization
course
BION32 20122
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
3915256
date added to LUP
2013-07-01 15:21:44
date last changed
2013-07-01 15:21:44
@misc{3915256,
  abstract     = {Abstract 

A radar study was performed to compare flight parameters between sparrowhawks and common buzzards during autumn migration at the Falsterbo peninsula, Sweden. Common buzzards had higher flight altitudes and were more selective for wind, yet their air - and cross-country speeds were lower than those of sparrowhawks. Furthermore, common buzzards had higher glide ratio, but lower airspeed while gliding. Moreover, when subdividing birds into two categories of forward and reverse migrants, differences were also observed within the species. Forward migrating sparrowhawks had highest airspeeds, but reverse migrating sparrowhawks had highest groundspeeds. In addition, forward migrating common buzzards had higher groundspeeds than reverse migrating common buzzards. Forward migrating sparrowhawks and common buzzards had less scattered heading directions, but more scattered track directions than reverse migrants. No difference was observed in forward migrating sparrowhawks and common buzzards’ migratory directions or flight paths in relation to topography. Differences between the species were not only caused by their morphology or flight style preference, but also by environmental factors, such as wind speed and direction and foraging opportunity for sparrowhawks. Results from similar studies are also compared and discussed.

Popular science summary:

Tracking birds with a radar

I have been tracking raptors, common buzzards and sparrowhawks migrating at Falsterbo peninsula, southwestern part of Sweden. This place provides a wonderful opportunity to study bird migration as many birds try to avoid large water barriers and concentrate in places such as Falsterbo with short distance from one coast to another. The aim of the study was to compare flight performance between sparrowhawks and common buzzards by the following parameters: flight altitude and flight speed, performance during soaring/climbing and gliding phases, flight directions, and flight paths over Falsterbo peninsula in relation to topography and wind direction. 
The radar provided an opportunity to track an individual bird to a distance of more than 10 km. By measuring the wind speed and direction I could gather information on bird’s speed and direction relative to the air and to the ground, which is the result of the wind effect. 
Common buzzards were flying at higher altitudes and were more selective of better winds than sparrowhawks, yet sparrowhawks had higher air-, and cross-country speeds. Moreover, common buzzards had higher glide ratio, but lower sink speed and airspeed while gliding. No significant difference in mean heading and track directions between forward migrating birds was found. In addition no significant difference was found in flight paths in relation to topography. 
These results could help evaluate the future effects of climate change on migrating raptors at higher latitudes and the interspecific differences in reaction to the changes. 

Supervisor: Thomas Alerstam 
Master´s Degree Project in Animal Ecology, 45 credits, 2013 
Department of Biology, Lund University},
  author       = {Malmiga, Gintaras},
  language     = {eng},
  note         = {Student Paper},
  title        = {Interspecific comparison of the flight performance between sparrowhawks and common buzzards migrating at the Falsterbo peninsula: a radar study},
  year         = {2013},
}