An analysis of inter-annual and withinwinter survival among rural and urban great tits (Parus major)
(2020) BION03 20192Degree Projects in Biology
- Abstract
- Birds endure ecological constraints during winter in temperate regions where critical resources vary significantly between urban and rural sites, influencing survival rate. Warmer temperatures and artificial food sources have led to an increase in urban avian winter abundance whereas birds in colder, rural ecosystems are more reliant on scarce natural food sources but subject to less human disturbance. We utilized capture-recapture data to study annual survival of adult and juvenile great tits captured from the 2017-2019 breeding seasons as well as within-winter survival of adults captured during the 2019-2020 winter season in urban and rural nest boxes located in southern Sweden. We hypothesized a higher urban survival rate than rural... (More)
- Birds endure ecological constraints during winter in temperate regions where critical resources vary significantly between urban and rural sites, influencing survival rate. Warmer temperatures and artificial food sources have led to an increase in urban avian winter abundance whereas birds in colder, rural ecosystems are more reliant on scarce natural food sources but subject to less human disturbance. We utilized capture-recapture data to study annual survival of adult and juvenile great tits captured from the 2017-2019 breeding seasons as well as within-winter survival of adults captured during the 2019-2020 winter season in urban and rural nest boxes located in southern Sweden. We hypothesized a higher urban survival rate than rural conspecifics as well as a correlation between great tit body mass and survival. Survival analyses for MARK Recapture Software provided survival and recapture estimates for first year survival as well as adult survival, adding fixed effects to analyze the effect of city, sex, and age on survival. In addition, our within-winter survival models focused on survival estimates specifically for birds captured during the 2020 winter that include fixed effects and biometrics. Higher survival was found in rural habitats during the 2017-2018 period for adults and juveniles, while urban habitat survival was higher in all subsequent intervals. Our results indicated that city and sex were found as significant determinants for survival variation in our annual estimates where apparent survival for Malmö was higher than Helsingborg and Gothenburg, while males survival was higher than females. Age was the only variable determining variation in our within-winter data, resulting in higher survival rates of older birds. (Less)
- Popular Abstract
- Annual and winter survival of rural and urban great tits (Parus major)
Urbanization has been shown to affect bird species either positively or negatively, leading to an increase or a decrease in populations, respectively. Winter is a demanding season where natural food is in short supply and lower temperatures require more food intake than in warmer seasons. Cities may be more suitable winter habitats for birds that provide artificial food and warmer temperatures. Although human disturbance is reduced, rural birds have to rely more on natural food to survive and avoid a higher amount of predators. This study aims to investigate rural and urban annual and within-winter survival of juvenile and adult great tits (Parus major) in southern... (More) - Annual and winter survival of rural and urban great tits (Parus major)
Urbanization has been shown to affect bird species either positively or negatively, leading to an increase or a decrease in populations, respectively. Winter is a demanding season where natural food is in short supply and lower temperatures require more food intake than in warmer seasons. Cities may be more suitable winter habitats for birds that provide artificial food and warmer temperatures. Although human disturbance is reduced, rural birds have to rely more on natural food to survive and avoid a higher amount of predators. This study aims to investigate rural and urban annual and within-winter survival of juvenile and adult great tits (Parus major) in southern Sweden, predicting higher urban survival based on food abundance and warmer temperatures. Additionally, we examined if body mass would influence within-winter survival.
Birds were captured in rural and urban nest boxes in Malmö, Helsingborg, and Gothenburg. Over the 2017-2019 breeding seasons, breeding adults were captured and ringed in nest boxes while juveniles were ringed at 14 days old. During winter 2019-2020, adults were captured in each rural and urban site at night. Age, sex, wing length, and body mass were recorded for each captured adult, while wing length and mass were recorded for juveniles. The effect of each variable on rural and urban survival was tested.
We have found that survival probabilities were higher in rural environments from 2017-2018, then our subsequent estimates showed that urban habitats were more suitable for birds. Adults and juveniles residing in Malmö had higher chances of surviving throughout the study than birds in Helsingborg and Gothenburg. In addition, males had higher survival probabilities than females.
However, we could not determine survival probability differences between rural and urban habitats for winter 2019-2020. The only determinable impact was that birds in their third year or more had higher probabilities of surviving, likely due to the experience in surviving winter for older birds. We were unable to find body mass differences between rural and urban habitats for surviving winter 2019-2020. Conditions in our samples potentially started out more suitable in all rural sites, given that annual rural survival was higher in 2017-2018. Natural food abundance was potentially higher and weather conditions were better. The subsequent higher urban survival from 2018-2020 suggests better suitability for the urban habitats. Warmer urban temperatures decrease costs of winter thermoregulation and accelerate spring time conditions, bringing earlier insect abundance for the coming breeding season. Supplementary food may have been more abundant in cities and offered good nutrition for the birds, allowing low and high quality individuals to feed and survive.
Our study has overall found that urban survival was higher in some years, but not all. Habitat survival is likely dependent on environmental factors where food and weather conditions can vary by year. Rural forests may have some good years for birds providing great living conditions and survival can be expected to be higher in these ecosystems. But when rural conditions are not good, higher urban survival may be expected due to year-round food and temperature benefits. The differences in habitat survival can also help further determine the impact that humans have on avian populations as urbanization grows, and could indicate if living among humans is causing too much constraint for birds.
Advisors: Caroline Isaksson, Hannah Watson
Department of Biology, Evolutionary Ecology Unit (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9022084
- author
- von Känel, Julian
- supervisor
- organization
- course
- BION03 20192
- year
- 2020
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9022084
- date added to LUP
- 2020-06-24 13:51:02
- date last changed
- 2020-06-24 13:51:02
@misc{9022084,
abstract = {{Birds endure ecological constraints during winter in temperate regions where critical resources vary significantly between urban and rural sites, influencing survival rate. Warmer temperatures and artificial food sources have led to an increase in urban avian winter abundance whereas birds in colder, rural ecosystems are more reliant on scarce natural food sources but subject to less human disturbance. We utilized capture-recapture data to study annual survival of adult and juvenile great tits captured from the 2017-2019 breeding seasons as well as within-winter survival of adults captured during the 2019-2020 winter season in urban and rural nest boxes located in southern Sweden. We hypothesized a higher urban survival rate than rural conspecifics as well as a correlation between great tit body mass and survival. Survival analyses for MARK Recapture Software provided survival and recapture estimates for first year survival as well as adult survival, adding fixed effects to analyze the effect of city, sex, and age on survival. In addition, our within-winter survival models focused on survival estimates specifically for birds captured during the 2020 winter that include fixed effects and biometrics. Higher survival was found in rural habitats during the 2017-2018 period for adults and juveniles, while urban habitat survival was higher in all subsequent intervals. Our results indicated that city and sex were found as significant determinants for survival variation in our annual estimates where apparent survival for Malmö was higher than Helsingborg and Gothenburg, while males survival was higher than females. Age was the only variable determining variation in our within-winter data, resulting in higher survival rates of older birds.}},
author = {{von Känel, Julian}},
language = {{eng}},
note = {{Student Paper}},
title = {{An analysis of inter-annual and withinwinter survival among rural and urban great tits (Parus major)}},
year = {{2020}},
}