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The Faroese 1981 bird census revisited - fewer birds in 2020

Kongsbak, Ása Diana Krossá (2020) BIOM02 20201
Degree Projects in Biology
Abstract
A prerequisite for the effective conservation of species, is the accurate assessment of a species’ distribution and numbers. In order to look into the population sizes of birds, a quantitative atlas project from 1981 included a total count of the inland birds in the Faroe Islands. The aim for my thesis was to look at the population changes from 1981 until 2020, by repeating the 1981 atlas project, but on a smaller scale, by doing a total count on the island Vágoy. The census was carried out between June 16th and July 2nd by five persons. The statistical test applied was the Wilcoxon Signed Rank test that showed no significant differences in rank of bird numbers, for all but the Great Skua (Stercorarius skua) that increased in rank from... (More)
A prerequisite for the effective conservation of species, is the accurate assessment of a species’ distribution and numbers. In order to look into the population sizes of birds, a quantitative atlas project from 1981 included a total count of the inland birds in the Faroe Islands. The aim for my thesis was to look at the population changes from 1981 until 2020, by repeating the 1981 atlas project, but on a smaller scale, by doing a total count on the island Vágoy. The census was carried out between June 16th and July 2nd by five persons. The statistical test applied was the Wilcoxon Signed Rank test that showed no significant differences in rank of bird numbers, for all but the Great Skua (Stercorarius skua) that increased in rank from 1981 to 2020. However, most species showed a change in percentage >25%, more than half of them decreasing, and the overall count of individual birds decreased by 25.4% from 1981 to 2020. Clearly, compared to the 1981 census, many of the bird species have experienced big changes in population sizes, many of which can possibly be attributed to factors such as food shortage, including the decreased availability of fish discards, and the increased number of certain predators. The changes in population sizes on the western half of Vágoy do not follow the changes seen in European populations very well, and differing threats and environmental conditions are probably a big part of the reasons for this. For future studies, it would be highly beneficial to commence a Common Bird Monitoring Scheme in the Faroe Islands, like the ones we see in most other European countries. (Less)
Popular Abstract
THE FAROESE BIRD POPULATION SIZES IN 1981 AND 2020


To be able to protect a species, we must first of all know where it is and how many individuals there are. An atlas project maps the distribution of a group of species and looks into whether the species are breeding at a particular site or not. One quantitative atlas census was carried out in 1981 on the island group of the Faroe Islands, and a new one was past due. My project took on the quantitative atlas census on a smaller scale, looking into the distribution and size of the bird populations on one of its larger islands, Vágoy. The results can help make it clear which species are vulnerable and which are not, and if the bird numbers are increasing or decreasing overall.

The... (More)
THE FAROESE BIRD POPULATION SIZES IN 1981 AND 2020


To be able to protect a species, we must first of all know where it is and how many individuals there are. An atlas project maps the distribution of a group of species and looks into whether the species are breeding at a particular site or not. One quantitative atlas census was carried out in 1981 on the island group of the Faroe Islands, and a new one was past due. My project took on the quantitative atlas census on a smaller scale, looking into the distribution and size of the bird populations on one of its larger islands, Vágoy. The results can help make it clear which species are vulnerable and which are not, and if the bird numbers are increasing or decreasing overall.

The atlas project from 1981 included the land and freshwater birds of the Faroe Islands, as well as the gulls and terns. The census was carried out between June 12th – July 3rd by 37 experienced Nordic ornithologists. My project copied the 1981 census to the highest degree possible, and included the same birds in roughly the same period (June 16th - July 2nd). However, in my census 5 people covered 11 routes on the western half of the island Vágoy.

We looked at differences in rank of bird numbers between the two years, as well as the percentage differences in population sizes to show the direction of change.

Fewer birds in 2020 than in 1981
We could see no significant differences in rank of bird numbers, for all but the Great Skua (Stercorarius skua) that showed a higher rank in 2020 than in 1981.
However, most species showed a change in percentage >25%, more than half of them decreasing. To illustrate the differences, we have Fig. 1. As we can see in Fig. 1, some species had a big decrease in bird numbers from 1981 to 2020, and the overall count of individual birds actually decreased by 25.6% in this period. Why these big differences are seen is not known, but much of it can likely be attributed to factors such as food shortage, including the decreased availability of fish discards, and the increased number of certain predators.

Overall, the changes in bird population sizes do not follow the European population changes very well. For future studies, it would be highly beneficial to start a Common Bird Monitoring Scheme in the Faroe Islands, like the ones we see in most other European countries.

Master’s Degree Project in Biology, 30 credits, 2020
Department of Biology, Lund University

Advisor: Åke Lindström
Professor in animal ecology at the Department of Biology, Faculty of Science (Less)
Please use this url to cite or link to this publication:
author
Kongsbak, Ása Diana Krossá
supervisor
organization
course
BIOM02 20201
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
9031878
date added to LUP
2020-11-12 12:04:43
date last changed
2020-11-12 12:04:43
@misc{9031878,
  abstract     = {A prerequisite for the effective conservation of species, is the accurate assessment of a species’ distribution and numbers. In order to look into the population sizes of birds, a quantitative atlas project from 1981 included a total count of the inland birds in the Faroe Islands. The aim for my thesis was to look at the population changes from 1981 until 2020, by repeating the 1981 atlas project, but on a smaller scale, by doing a total count on the island Vágoy. The census was carried out between June 16th and July 2nd by five persons. The statistical test applied was the Wilcoxon Signed Rank test that showed no significant differences in rank of bird numbers, for all but the Great Skua (Stercorarius skua) that increased in rank from 1981 to 2020. However, most species showed a change in percentage >25%, more than half of them decreasing, and the overall count of individual birds decreased by 25.4% from 1981 to 2020. Clearly, compared to the 1981 census, many of the bird species have experienced big changes in population sizes, many of which can possibly be attributed to factors such as food shortage, including the decreased availability of fish discards, and the increased number of certain predators. The changes in population sizes on the western half of Vágoy do not follow the changes seen in European populations very well, and differing threats and environmental conditions are probably a big part of the reasons for this. For future studies, it would be highly beneficial to commence a Common Bird Monitoring Scheme in the Faroe Islands, like the ones we see in most other European countries.},
  author       = {Kongsbak, Ása Diana Krossá},
  language     = {eng},
  note         = {Student Paper},
  title        = {The Faroese 1981 bird census revisited - fewer birds in 2020},
  year         = {2020},
}