| 1. |
- Nilsson, Jan-Åke, et al.
(författare)
-
Effects of Dispersal Date on Winter Flock Establishment and Social Dominance in Marsh Tits Parus palustris
- 1988
-
Ingår i: Journal of Animal Ecology. - : JSTOR. - 1365-2656 .- 0021-8790. ; 57:3, s. 917-928
-
Tidskriftsartikel (refereegranskat)abstract
- (1) We studied the effect of sex, size, age and prior occupancy on social dominance winter flock establishment in a population of marsh tits Parus palustris L. (2) When sex was accounted for, time of establishment in the winter flock-prior occupancy, was critical for the outcome of later aggressive interactions juveniles within flocks. Residents won all interactions with intruders irrespective controlling for sex. (3) Success in, and timing of, establishment were closely linked with hatching lower proportion of late-hatched than early-hatched juveniles became established winter flocks; they also became established later. Even small differences in hatching greatly influenced dominance and the probability of becoming established flock. (4) Since early establishment depends on early hatching, dominance and survival juveniles are determined by how early their parents start breeding. Furthermore, will be strong selection for quick establishment after
|
|
| 2. |
- Smith, Henrik G., et al.
(författare)
-
Intrasexual competition among polygynously mated female starlings (Sturnus vulgaris)
- 1994
-
Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 5, s. 57-63
-
Tidskriftsartikel (refereegranskat)abstract
- In southern Sweden, the starling (Sturnus vulgaris) has a variable mating system with some males mating monogamously and others attracting several females. Mating status affected the reproductive success of females: monogamous and primary females laid larger clutches and fledged more and heavier young than secondary females. This pattern was explained by female competition for male help, with the male primarily helping the offspring of highest value (i.e., the oldest brood). However, when the nesting attempt of the primary female failed, the success of the secondary female increased to the same level as that for primary and monogamous females. The success of the secondary female in terms of fledging success and fledgling size was higher when the secondary female hatched her eggs soon after the primary female. This was due to the fact that a male divided his effort between his broods when the age difference between broods was small
|
|
| 3. |
- Bruun, Måns, et al.
(författare)
-
Polygynous male starlings allocate parental effort according to relative hatching date
- 1997
-
Ingår i: Animal Behaviour. - : Elsevier BV. - 1095-8282 .- 0003-3472. ; 54, s. 73-79
-
Tidskriftsartikel (refereegranskat)abstract
- In many polygynous bird species, males allocate most of their parental effort to their primary females’ broods. There are several hypotheses that may explain this: the relative reproductive value of the brood, the energetic demand of the brood, the genetic quality of the female and the certainty of fatherhood may all be higher for the primary females’ broods. Since these parameters may covary in nature, experiments are necessary to determine their importance. Bigynous male European starlings,Sturnus vulgarispredominantly incubated the eggs and fed the nestlings of their primary females. In an experiment we altered the order in which the clutches hatched by exchanging the primary and secondary females’ eggs before hatching. Even though experimental males mostly incubated their primary females’ clutches, they predominantly fed the nestlings of the secondary female. Experimental males fed secondary females’ nestlings significantly more than control males did. In fact, experimental males invested in their secondary females’ broods to the same extent as control males invested in their primary females’ broods. This result demonstrates that males use relative brood age to decide how to allocate their parental effort between their broods which has important implications for the evolution of the starling mating system.
|
|
| 4. |
- Smith, Henrik G., et al.
(författare)
-
Intraspecific variation in migratory pattern of a partial migrant, the Blue Tit (Parus caeruleus) : An evaluation of different hypotheses
- 1987
-
Ingår i: The Auk. - : Oxford University Press (OUP). - 0004-8038 .- 1938-4254. ; 104:1, s. 109-115
-
Tidskriftsartikel (refereegranskat)abstract
- To evaluate hypotheses explaining intraspecific variation in migratory behavior in partial migrants, a local population of Blue Tits (Parus caeruleus) was studied in southern Sweden. Birds born in the study area and recaptured there in winter were compared with birds recaptured at a nearby bird station where a large number of migrant Blue Tits were passing. By comparing sex ratios among migrants and residents, we concluded that, among juveniles, more than 40% of the females and a significant proportion of the males migrated, while considerably fewer adult females and virtually no adult males did so. Migrant and resident Blue Tits did not differ in size as nestlings, but more late- than early-hatched males migrated. No differences in hatching date were determined for females, presumably because most of them migrated. Our findings are consistent with the "dominance hypothesis" as an explanation of partial migration, i.e. that the individuals lowest in rank migrate. The fitness gain that leads dominants to stay as residents may be lower winter mortality or a higher probability of establishing a territory in spring. In either case, keener competition for breeding territories among males than among females as a cause tor higher residency cannot be excluded.
|
|
| 5. |
- Smith, Henrik G.
(författare)
-
Seasonal Decline in Clutch Size of the Marsh Tit (Parus palustris) in Relation to Date-Specific Survival of Offspring
- 1993
-
Ingår i: Auk. - : Oxford University Press (OUP). - 0004-8038. ; 110, s. 889-899
-
Tidskriftsartikel (refereegranskat)abstract
- This paper documents and evaluates seasonal trends in reproductive performance in the Marsh Tit (Parus palustris) in southern Sweden. Clutch size decreased for nests started later in the season. This pattern held true both for second-year and older females when analyzed separately. Individual females adjusted clutch size in relation to the relative time of season they produced a clutch a particular year. The seasonal decline in clutch size was also evident for clutches produced in the same territory at different parts of the season in different years. Females breeding for several years demonstrated a high consistency in relative laying date and clutch size. The same was not true for males or for territories. The length of the incubation period normally decreased with season. Nestling mass and survival did not show any systematic seasonal trend. Nest predation was probably more prevalent late in the season. Fledglings that hatched later had poorer survival until autumn. This effect was evident for males, but not for females. Hatching date did not influence fledglings' survival to the next breeding season, but sample sizes were small. I suggest that the Marsh Tit adjusts clutch size to the survival probability of nestlings, this being affected by the probability of nest predation and by fledgling survival. Hence, late-laying females are not prepared to accept as large reproductive costs as early laying females.
|
|
| 6. |
- Granbom, Martin, et al.
(författare)
-
Food limitation during breeding in a heterogeneous landscape
- 2006
-
Ingår i: The Auk. - 0004-8038. ; 123:1, s. 97-107
-
Tidskriftsartikel (refereegranskat)abstract
- Breeding success in birds may be determined by the availability of food that parents can provide to growing nestlings. A standard method for testing the occurrence of food limitation is to provide supplemental food during different parts of the breeding period. If there is spatial variation in the strength of food limitation, the effect of such an experiment should also vary spatially. We investigated whether the strength of food limitation during nestling rearing in the European Starling (Sturnus vulgaris) was related to the management intensity of agricultural landscapes. We fed birds mealworms during the nestling period in landscapes with high or low local availability of pasture, the preferred foraging habitat. Both habitat and food supplementation affected growth and survival of nestlings; the effects of the food-supplementation experiment were generally stronger than those of habitat. Mortality mainly struck the last-hatched chick. Both habitat and food supplementation positively affected nestling growth, measured as nestling tarsus length. In addition, food supplementation positively affected feather growth and asymptotic mass. Contrary to expectation, no interactions existed between effects of habitat and food supplementation, which suggests that breeding success was limited by food availability in both landscapes. Potential reasons for this lack of effect are parental compensation and low statistical power. Also, breeding densities were higher in landscapes with more pastures, possibly equalizing the per-capita availability of food. Thus, our results demonstrate that reproductive success was limited by availability of food when local availability of preferred foraging habitat was either low or high, but fail to demonstrate spatial variation in the strength of food limitation.
|
|
| 7. |
- Karlsson, Maria, et al.
(författare)
-
House sparrow Passer domesticus survival is not associated with MHC-I diversity, but possibly with specific MHC-I alleles
- 2015
-
Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 46:2, s. 167-174
-
Tidskriftsartikel (refereegranskat)abstract
- The MHC (Major Histocompatibility Complex) plays an important role in the immune system of vertebrates. MHC genes are extremely polymorphic and this variation is considered to be maintained by selection from pathogens. We investigate whether MHC diversity (number of different alleles per individual) affects the survival and recruitment of nestling house sparrows. We hypothesize that individuals with higher MHC diversity can recognize and combat a wider range of pathogens, and therefore are more likely to survive and recruit into the breeding population. Additionally, we hypothesize that specific MHC class I alleles (MHC-I) could be associated with survival and recruitment. We screened MHC-I genotypes in 518 house sparrow chicks hatched on Lundy Island but we found no evidence for a relationship between nestling survival, post-fledging survival or recruitment success with MHC diversity. Then we investigated effects of specific MHC-I alleles in 195 individuals from a single cohort. Twenty-one MHC-I alleles were tested for relationships with nestling survival, post-fledging survival and recruitment, and we detected associations with survival for three different alleles. This pattern was, however, not different to what would be expected from random, so we could not conclude that particular MHC-I alleles are associated with survival in house sparrows on Lundy Island. Nonetheless, one of these alleles (1105) showed both a tendency for a higher probability of surviving in nestlings, and a significant association with survival in fledglings. We envision that allele 1105 could be an interesting candidate gene for testing associations with survival in house sparrows in the future.
|
|
