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Boldness and parental care: nest protection and food provisioning in great reed warblers in relation to social mating status, sex and social partner behavior

Bensen, Erik (2020) BION03 20192
Degree Projects in Biology
Abstract
The notion of personalities in animals has been used as a means of contextualizing consistent trends in behavior. To be classified as a personality, the behavior must be both consistent over time, and have a heritable component. Research into the personality of boldness, particularly in the defense of the nest, and the relation it has with provisioning young, has yielded insights into behavioral constructs and into the fitness tradeoffs that result from those behaviors. Seeking to better understand how behavior functions in a socially polygynous system, we compared the nest defense boldness between parents at the nest, and we compared nest defense boldness with the provisioning efforts of each parent. The first hypothesis was that there... (More)
The notion of personalities in animals has been used as a means of contextualizing consistent trends in behavior. To be classified as a personality, the behavior must be both consistent over time, and have a heritable component. Research into the personality of boldness, particularly in the defense of the nest, and the relation it has with provisioning young, has yielded insights into behavioral constructs and into the fitness tradeoffs that result from those behaviors. Seeking to better understand how behavior functions in a socially polygynous system, we compared the nest defense boldness between parents at the nest, and we compared nest defense boldness with the provisioning efforts of each parent. The first hypothesis was that there would be a correlation of nest defense scores between the parents at monogamous and primary nests, but not in secondary nests based on the relative investment of the parents. The results of this study supported this hypothesis. The second hypothesis was that an inverse correlation between nest defense scores and provisioning behavior would be found in secondary females, as they would be more time and energy constrained due to limited parental care help from their male. This relation was analyzed with two metrics for provisioning effort (feeding visit rate and prey mass rate) and was found to have no correlation among either sex or subsets of nest mating status, rejecting the second hypothesis. Trends hinted within primary males and secondary females do merit future examination. (Less)
Popular Abstract
Nest Protection and Nestling Feeding in the Great Reed Warbler (Acrocephalus arundinaceus)

The loss of a nest to predation represents one of the most common causes of nest failure. To minimize this risk, bird will defend their nest. The effort put into nest defense is largely influenced by the personality of the bird, in relation to the trait of boldness, and investment of the parents into the nest. The aim of this study is to examine nest defense behavior in the socially polygynous great reed warbler (Acrocephalus arundinaceus) to determine if defensive efforts between parents is impacted by polygyny, and if the relationship between nest defensive and nestling feeding efforts is affected by the mating status of the nest.

This study... (More)
Nest Protection and Nestling Feeding in the Great Reed Warbler (Acrocephalus arundinaceus)

The loss of a nest to predation represents one of the most common causes of nest failure. To minimize this risk, bird will defend their nest. The effort put into nest defense is largely influenced by the personality of the bird, in relation to the trait of boldness, and investment of the parents into the nest. The aim of this study is to examine nest defense behavior in the socially polygynous great reed warbler (Acrocephalus arundinaceus) to determine if defensive efforts between parents is impacted by polygyny, and if the relationship between nest defensive and nestling feeding efforts is affected by the mating status of the nest.

This study was conducted on the breeding population of great reed warblers at Lake Kvismaren during the spring and summer of 2019. Data for nest defense behavior was obtained through researcher visits to the nest, which would prompt a nest defense response. Parents were given a composite score reflecting the distance at which the were from the nest/researcher, and the intensity of vocalizations they were making. Compact cameras were placed at active nests to record the nestling feeding behavior when the chicks were one week old. These recordings were later reviewed to identify the feeding efforts of each parent by both frequency and type of prey.

We found among the whole population sampled, that the intensity in nest defense response was correlated between males and females at the same nest. When examining the primary nests, this correlation was found to be stronger and more significant. This correlation was not found to be significant when comparing parents in the secondary nests. Tests done on polygynous males found that response strength was higher in their primary nest compared to their secondary nests, and that response strength was correlated between the primary and secondary nests, meaning a stronger response in the primary nest was followed by a stronger response in the secondary nests. The behaviors of nestling feeding and nest defense were found have an uncorrelated relationship in this study, across both sexes and mating status of the nests. These trends were true for both feeding measures, the frequency of feeding and the mass of prey, when compared to the response strength of nest defense. The closest measure to significance was a positive correlation between the rate of feeding visits and nest defense strength in the first nests of males.

Our study found the relationship between the defensive efforts of the parents was correlated as expected in relation to the investment associated with the nests mating status. The trends within the polygynous males display appropriate plasticity in behavior yet show a consistent separation between the bold and shy individuals sampled. The lack of a correlation between nestling feeding and nest defense indicates that there is not a tradeoff between these behaviors, as seen in other species.

Advisor: Dennis Hasselquist
Department of Biology, MEMEG, Lund University (Less)
Please use this url to cite or link to this publication:
author
Bensen, Erik
supervisor
organization
course
BION03 20192
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
9038378
date added to LUP
2021-01-27 14:37:16
date last changed
2021-01-27 14:37:16
@misc{9038378,
  abstract     = {The notion of personalities in animals has been used as a means of contextualizing consistent trends in behavior. To be classified as a personality, the behavior must be both consistent over time, and have a heritable component. Research into the personality of boldness, particularly in the defense of the nest, and the relation it has with provisioning young, has yielded insights into behavioral constructs and into the fitness tradeoffs that result from those behaviors. Seeking to better understand how behavior functions in a socially polygynous system, we compared the nest defense boldness between parents at the nest, and we compared nest defense boldness with the provisioning efforts of each parent. The first hypothesis was that there would be a correlation of nest defense scores between the parents at monogamous and primary nests, but not in secondary nests based on the relative investment of the parents. The results of this study supported this hypothesis. The second hypothesis was that an inverse correlation between nest defense scores and provisioning behavior would be found in secondary females, as they would be more time and energy constrained due to limited parental care help from their male. This relation was analyzed with two metrics for provisioning effort (feeding visit rate and prey mass rate) and was found to have no correlation among either sex or subsets of nest mating status, rejecting the second hypothesis. Trends hinted within primary males and secondary females do merit future examination.},
  author       = {Bensen, Erik},
  language     = {eng},
  note         = {Student Paper},
  title        = {Boldness and parental care: nest protection and food provisioning in great reed warblers in relation to social mating status, sex and social partner behavior},
  year         = {2020},
}