Advanced

Brood parasitic European starlings do not lay high-quality eggs

Pilz, KM; Smith, Henrik LU and Andersson, M (2005) In Behavioral Ecology 16(3). p.507-513
Abstract
Chicks of obligate brood parasites employ a variety of morphological and behavioral strategies to outcompete nest mates. Elevated competitiveness is favored by natural selection because parasitic chicks are not related to their host parents or nest mates. When chicks of conspecific brood parasites (CBPs) are unrelated to their hosts, they and their parents would also benefit from traits that enhance competitiveness. However, these traits must be inducible tactics in CBPs, since conspecific brood parasitism (CBP) is facultative. Such tactics could be induced by resources passed to offspring through the egg. Thus, females engaging in CBP should allocate to their eggs resources that will enhance offspring competitiveness. We tested this... (More)
Chicks of obligate brood parasites employ a variety of morphological and behavioral strategies to outcompete nest mates. Elevated competitiveness is favored by natural selection because parasitic chicks are not related to their host parents or nest mates. When chicks of conspecific brood parasites (CBPs) are unrelated to their hosts, they and their parents would also benefit from traits that enhance competitiveness. However, these traits must be inducible tactics in CBPs, since conspecific brood parasitism (CBP) is facultative. Such tactics could be induced by resources passed to offspring through the egg. Thus, females engaging in CBP should allocate to their eggs resources that will enhance offspring competitiveness. We tested this prediction in a population of European starlings (Sturnus vulgaris) breeding in southern Sweden. Previous research showed that almost all CBPs in this population are floater females that have yet to breed in the current season. We identified putative brood parasitic eggs through monitoring egg laying and verified parasitism using protein fingerprinting. We then determined whether parasitic eggs were larger, larger-yolked, or had higher concentrations of yolk testosterone or androstenedione than control eggs. The 14 brood parasitic eggs laid in active nests (those with clutches of at least two eggs that were eventually incubated) did not differ from controls in any of these characteristics. Ten dumped eggs, laid in nonactive nest-boxes or on the ground, were smaller and smaller-yolked than control eggs but did not differ in yolk androgen concentrations. The failure of our prediction could be the result of high costs of investing in eggs, lack of competition-based benefits for chicks, or physiological constraints on egg manipulation. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Behavioral Ecology
volume
16
issue
3
pages
507 - 513
publisher
Oxford University Press
external identifiers
  • wos:000228402100002
  • scopus:19344372278
ISSN
1045-2249
DOI
10.1093/beheco/ari017
language
English
LU publication?
yes
id
6cdaa392-b768-4444-961d-f6c21f8b610f (old id 145393)
date added to LUP
2007-06-25 15:38:27
date last changed
2017-01-01 04:40:20
@article{6cdaa392-b768-4444-961d-f6c21f8b610f,
  abstract     = {Chicks of obligate brood parasites employ a variety of morphological and behavioral strategies to outcompete nest mates. Elevated competitiveness is favored by natural selection because parasitic chicks are not related to their host parents or nest mates. When chicks of conspecific brood parasites (CBPs) are unrelated to their hosts, they and their parents would also benefit from traits that enhance competitiveness. However, these traits must be inducible tactics in CBPs, since conspecific brood parasitism (CBP) is facultative. Such tactics could be induced by resources passed to offspring through the egg. Thus, females engaging in CBP should allocate to their eggs resources that will enhance offspring competitiveness. We tested this prediction in a population of European starlings (Sturnus vulgaris) breeding in southern Sweden. Previous research showed that almost all CBPs in this population are floater females that have yet to breed in the current season. We identified putative brood parasitic eggs through monitoring egg laying and verified parasitism using protein fingerprinting. We then determined whether parasitic eggs were larger, larger-yolked, or had higher concentrations of yolk testosterone or androstenedione than control eggs. The 14 brood parasitic eggs laid in active nests (those with clutches of at least two eggs that were eventually incubated) did not differ from controls in any of these characteristics. Ten dumped eggs, laid in nonactive nest-boxes or on the ground, were smaller and smaller-yolked than control eggs but did not differ in yolk androgen concentrations. The failure of our prediction could be the result of high costs of investing in eggs, lack of competition-based benefits for chicks, or physiological constraints on egg manipulation.},
  author       = {Pilz, KM and Smith, Henrik and Andersson, M},
  issn         = {1045-2249},
  language     = {eng},
  number       = {3},
  pages        = {507--513},
  publisher    = {Oxford University Press},
  series       = {Behavioral Ecology},
  title        = {Brood parasitic European starlings do not lay high-quality eggs},
  url          = {http://dx.doi.org/10.1093/beheco/ari017},
  volume       = {16},
  year         = {2005},
}