Breeding success of the great skua (Stercorarius skua) in East Iceland
(2024) BION02 20231Degree Projects in Biology
- Abstract
- Understanding what influences reproduction within populations is important to assess what changes are happening, especially for species with declining populations. In this study, I focus on a large seabird, the great skua (Stercorarius skua) which have been shown to have declining population trends in most of their breeding range in recent years. Skuas are long-lived species with delayed sexual maturation and low yearly reproductive rates. Many factors can influence the reproduction of great skuas, such as pollutants, human disturbance, and climate.
This study was conducted over one breeding season in a colony in East Iceland, where previous studies have been limited. Main objectives were assessing the overall reproductive success of... (More) - Understanding what influences reproduction within populations is important to assess what changes are happening, especially for species with declining populations. In this study, I focus on a large seabird, the great skua (Stercorarius skua) which have been shown to have declining population trends in most of their breeding range in recent years. Skuas are long-lived species with delayed sexual maturation and low yearly reproductive rates. Many factors can influence the reproduction of great skuas, such as pollutants, human disturbance, and climate.
This study was conducted over one breeding season in a colony in East Iceland, where previous studies have been limited. Main objectives were assessing the overall reproductive success of the colony and what factors might influence it. In particular, the potential impact from human disturbance on breeding success was investigated, by evaluating the breeding success relative to distance from walking paths. I also investigated if nest position in breeding colony ( (Less) - Popular Abstract
- Breeding in man’s territory: What’s up with the skuas?
Reproduction in birds can be influenced by many different factors, such as human behaviour where the disturbance from humans can have either negative or positive impacts on species. Other factors which seem to have large impacts are for example pollutants and climate, which often stem from some type of human activity.
Here I investigate the breeding success of Great skuas (Stercorarius skua) in a colony in Iceland over one season. Great skuas are large seabirds which breed around the North Atlantic. The largest breeding populations can be found in Scotland and Iceland, but they also breed in Norway, the Faroe Islands and some in Russia and Ireland. The have declining... (More) - Breeding in man’s territory: What’s up with the skuas?
Reproduction in birds can be influenced by many different factors, such as human behaviour where the disturbance from humans can have either negative or positive impacts on species. Other factors which seem to have large impacts are for example pollutants and climate, which often stem from some type of human activity.
Here I investigate the breeding success of Great skuas (Stercorarius skua) in a colony in Iceland over one season. Great skuas are large seabirds which breed around the North Atlantic. The largest breeding populations can be found in Scotland and Iceland, but they also breed in Norway, the Faroe Islands and some in Russia and Ireland. The have declining populations where the most recent population estimation from 2018 was 16,000 to 17,000 breeding pairs. Iceland has the second largest population of great skuas after Scotland. The most resent population estimates for Iceland was conducted in the years of 1984-1985 where there were an estimates 5400 pairs, but since then populations have declined. Most pairs reside at the south-east part of the country, but large colonies can also be found in the east and north. Fieldwork for this study was done in a colony in east Iceland at a place called Húsey. Húsey is a popular destination for nature tourism with many different species of birds residing in the area, as well as a large seal colony residing in the nearby rivers. The nearby Húsey farm also offer horse-riding tours in the area of the colony.
Survival of nests until the eggs hatched and survival of chicks until they became fully or almost fledged was estimated by visiting the colony ten times and providing the chicks with rings to identify them. To further pinpoint what could influence the survival, a comparison was done on survival of both nests and chicks in an area where the density of nests was high as compared to where density was low. Comparing the survival of nests which were situated far from or near to any hiking and horse-riding paths was also included. Due to limited number of nests the results could not be confirmed statistically, but there where a tendency that survival of nests and chicks was higher in areas where nest density was high and at nests located further away from paths used by humans. This indicates that there are benefits to skuas of nesting at higher densities and where human disturbance is lower. However, there can also be a benefit of being so close to humans as hikers and horse-riders can drive away certain predators of eggs and chicks, such as the arctic fox (Vulpes lagopus), which is the main predator for the great skua in Iceland.
This study was done in the summer field season of 2022, which was a devastating year for the great skuas all around the North Atlantic due to the outbreak of highly pathogenic avian influenza (HPAI). This did have large impacts of survival that year and likely a reason that chick survival was rather low compared to other studies. Many adult birds were found dead which in turn impacted chick survival. This, alongside other factors which contribute to the overall population decline of great skuas is a wakeup call to further study and protect them before it will be too late.
Master’s Degree Project in Biology, Animal Ecology: 45 credits, 2024
Department of Biology, Lund University
Supervisor: Susanne Åkesson (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9176989
- author
- Sverrisdóttir, Kolbrún
- supervisor
- organization
- course
- BION02 20231
- year
- 2024
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9176989
- date added to LUP
- 2024-10-23 14:43:45
- date last changed
- 2024-10-23 14:43:45
@misc{9176989,
abstract = {{Understanding what influences reproduction within populations is important to assess what changes are happening, especially for species with declining populations. In this study, I focus on a large seabird, the great skua (Stercorarius skua) which have been shown to have declining population trends in most of their breeding range in recent years. Skuas are long-lived species with delayed sexual maturation and low yearly reproductive rates. Many factors can influence the reproduction of great skuas, such as pollutants, human disturbance, and climate.
This study was conducted over one breeding season in a colony in East Iceland, where previous studies have been limited. Main objectives were assessing the overall reproductive success of the colony and what factors might influence it. In particular, the potential impact from human disturbance on breeding success was investigated, by evaluating the breeding success relative to distance from walking paths. I also investigated if nest position in breeding colony (}},
author = {{Sverrisdóttir, Kolbrún}},
language = {{eng}},
note = {{Student Paper}},
title = {{Breeding success of the great skua (Stercorarius skua) in East Iceland}},
year = {{2024}},
}