Advanced

Stopover ecology of the European nightjar Caprimulgus europaeus during autumn migration in south-eastern Sweden

Groth, Mattias (2017) BION01 20171
Degree Projects in Biology
Popular Abstract
Do European nightjars migrate via Öland in autumn?

Bird migration is a common phenomenon of the natural world with at least 4,000 species of birds being regular migrants. Many of those species have to cover long distances from breeding grounds in the northern hemisphere to wintering grounds in the tropics. They often face ecological barriers e.g. deserts or oceans with no food supply. Therefore it is essential for migratory birds to put on enough fat (fuel up) prior to crossings of such barriers. This so called ʻfuelling’ takes place on stopover sites where birds can rest and fuel up. In this study I investigated if and how European nightjars use southern Öland as a stopover site during autumn migration.

The European nightjar is a... (More)
Do European nightjars migrate via Öland in autumn?

Bird migration is a common phenomenon of the natural world with at least 4,000 species of birds being regular migrants. Many of those species have to cover long distances from breeding grounds in the northern hemisphere to wintering grounds in the tropics. They often face ecological barriers e.g. deserts or oceans with no food supply. Therefore it is essential for migratory birds to put on enough fat (fuel up) prior to crossings of such barriers. This so called ʻfuelling’ takes place on stopover sites where birds can rest and fuel up. In this study I investigated if and how European nightjars use southern Öland as a stopover site during autumn migration.

The European nightjar is a nocturnal/crepuscular tropical migrant that feeds on insects in flight. Its breeding range covers large parts of Europe including southern and eastern Sweden. As a long distance migrant it spends the winter in tropical Africa south of the Sahara desert. Hence, it has to face the long and dangerous journey over the Mediterranean Sea and the Sahara twice a year. In its breeding territory it prefers pine forest with openings, clearings, bogs etc. and sandy soil.

My study looked for the first time at fuelling rates (how fast a bird gains fat) of European nightjars at a stopover site on autumn migration. For this I spent six weeks (12th August until 23rd September 201) at the Ottenby Nature Reserve on Öland trying to catch as many migrating nightjars as possible. Furthermore, I deployed 12 radio transmitters to study their habitat use.

I caught in total 75 nightjars (69 juveniles, 6 adults) relatively evenly distributed over six weeks. Both adults and juveniles carried enough fat (fuel load) to be able to cross the Baltic Sea towards Poland in a single flight. Nightjars caught at Ottenby during autumn migration had on average higher fuel loads than birds caught at a breeding site in eastern Småland indicating that nightjars on Öland are indeed migrants. The fuelling rate of 10 recaptured nightjars was on average 0.4% of LBM (fat-free mass before fuelling) per day, which is quite low compared to other birds on autumn migration. The minimum stopover time (time between first capture and recapture) of recaptured birds was 4 days.
Radio-tagged birds spent the day roosting in the forest and were mainly active in open habitats during the night. Assuming birds leaving the area are migrating in a south, south-easterly direction, most radio-tagged individuals left on nights with moderate tailwinds and no precipitation which has been shown in other migratory species before.

My results demonstrate that European nightjars use southern Öland as a stopover site on autumn migration and provide first insights into fuelling rates and habitat use on a stopover site in northern Europe.



Master’s Degree Project in Animal Ecology, 45 credits, 2017
Department of Biology, Lund University

Advisor: Anders Hedenström
Animal Flight Lab, CAnMove (Less)
Please use this url to cite or link to this publication:
author
Groth, Mattias
supervisor
organization
course
BION01 20171
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8925004
date added to LUP
2017-09-07 16:23:31
date last changed
2017-09-07 16:23:31
@misc{8925004,
  author       = {Groth, Mattias},
  language     = {eng},
  note         = {Student Paper},
  title        = {Stopover ecology of the European nightjar Caprimulgus europaeus during autumn migration in south-eastern Sweden},
  year         = {2017},
}