Harem size, territory quality, and reproductive success in the redwinged blackbird (Agelaius phoeniceus)

1977 ◽  
Vol 55 (8) ◽  
pp. 1261-1267 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Raleigh J. Robertson
Keyword(s):  
Reproductive Success ◽  
Nest Site ◽  
Selective Advantage ◽  
Breeding Population ◽  
Territory Size ◽  
Agelaius Phoeniceus ◽  
Breeding Density ◽  
Territory Quality ◽  
Fledging Success ◽  
Harem Size

The relationships between harem size, territory size, nest site suitability, and fledging success were studied for a breeding population of redwinged blackbirds (Agelaius phoeniceus). Reproductive success was correlated negatively with female breeding density within territories and positively with territory quality as determined from nest site parameters. Harem size was not correlated with differences in either territory area or quality. From these results we suggest that some females were attracted to nest in territories in which their chances of successful reproduction were lower than if they had chosen other available territories. To explain the selective advantage of such choices, we postulate that females were choosing mates which would enhance their ultimate fitness rather than their immediate reproductive success.

Territory dynamics and patterns of female recruitment in Red-winged Blackbirds (Agelaius phoeniceus)

1987 ◽  
Vol 65 (3) ◽  
pp. 465-471 ◽  
Author(s):  
T. E. Dickinson ◽  
M. R. Lein
Keyword(s):  
Mating Systems ◽  
Nest Site ◽  
Active Role ◽  
Territory Size ◽  
Agelaius Phoeniceus ◽  
Nest Sites ◽  
Harem Size ◽  
Nesting Sites ◽  
Territory Dynamics

The territorial boundaries defended by male Red-winged Blackbirds (Agelaius phoeniceus) shifted over the course of the breeding season. The establishment of new males in a colony, the redefinition of boundaries among neighbors, and the recruitment of new females were all related to changes in boundary locations. No significant correlations were found between harem size and either territory size or the abundance of preferred nesting sites. High rates of aggressive interactions did, however, coincide with the recruitment of new females and accompanied territory shifts. Many boundary changes were associated with the guarding by males of females that were showing interest in nest sites outside the area formerly defended by the male. If a female's behavior in an area precipitates conflicts among neighboring males, then it could be a mechanism whereby females simultaneously compare the attributes of males and influence the quality of their territories. Such a mechanism would ensure that a female obtains what she has determined to be the best available nest site and a male that can defend her choice. A more active role for females should be included in models of the evolution of mating systems.

Which characteristics might selection favour as cues of female choice of mate in Red-winged Blackbirds?

1994 ◽  
Vol 72 (9) ◽  
pp. 1616-1624 ◽  
Author(s):  
Maynard L. Milks ◽  
Jaroslav Picman
Keyword(s):  
Reproductive Success ◽  
Nest Site ◽  
Female Mate Choice ◽  
Nest Defense ◽  
Agelaius Phoeniceus ◽  
Genetic Quality ◽  
Cistothorus Palustris ◽  
Site Characteristics ◽  
Mammalian Predators ◽  
Nest Height

In this study, we investigated potential cues determining choice of mate by female Red-winged Blackbirds (Agelaius phoeniceus) by examining male and nest-site characteristics that (i) affect the reproductive success of females, (ii) can be assessed by females prior to mating, and (iii) vary among potential mates, in 1983–1985. The 17 characteristics considered reflected the accessibility of redwing nests to mammalian predators and to Marsh Wrens (Cistothorus palustris), the importance of cooperation between female redwings in nest defense, and the paternal quality (feeding and defense of nestlings), genetic quality, physical condition, and size of redwing males. Only 4 characteristics, distance to nearest wren nest, distance to nearest simultaneously active conspecific nest, height of vegetation supporting the nest, and nest defense effort of males, met all of the above criteria in at least 1 year. Of these, proximity to wren nests appeared to satisfy the requirements most consistently in time and space, and thus might be the most likely to affect female redwing choice of mate. However, experimental manipulations are needed to ascertain whether any of these characteristics are cues of female mate choice in Red-winged Blackbirds.

EXPERIMENTAL EVIDENCE FOR THE COST OF POLYGYNY IN THE RED-WINGED BLACKBIRD AGELAIUS PHOENICEUS

Behaviour ◽  
2000 ◽  
Vol 137 (9) ◽  
pp. 1153-1173 ◽  
Author(s):  
Stanislav Pribil
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
Experimental Studies ◽  
Agelaius Phoeniceus ◽  
Lower Survival ◽  
Harem Size ◽  
Fledgling Survival ◽  
Provisioning Rate ◽  
The Difference ◽  
The Cost

AbstractI examined the effect of harem size on female reproductive success in the red - winged blackbird (Agelaius phoeniceus) in Ontario while controlling for the confounding effects of territory and male quality. Male territories were matched by their quality and harem sizes were manipulated by selective removal of females. The removals created monogamous and bigamous harems. Bigamous females fledged significantly fewer young than monogamous females, mainly due to higher predation on their nests. Young of the bigamous females were fed less frequently than young of the monogamous females (mainly due to reduced male assistance), but the difference was not significant. There was a positive relationship between parental provisioning rate and nestling body size. Young of the bigamous females fledged at smaller body size than young of the monogamous females. Because fledgling body size is related to post - fledgling survival, young of the bigamous females presumably experienced lower survival than young of the monogamous females. The lower number of fledglings, combined with their lower survival, suggests that the bigamous females produced fewer descendants than the monogamous females. I conclude that polygyny is costly to females in this population of the red - winged blackbird. Previous experimental studies demonstrated that females in this population prefer to settle with unmated males rather than already - mated males. In light of the present findings, the preferences appear adaptive, as they reduce the cost of polygyny. In Pennsylvania, Searcy (1988) reported that females settle independently of harem size and that harem size has no effect on their reproductive success. A comparison of the Ontario and Pennsylvania populations suggest that there are geographic differences in the effect of harem size on both female preferences and reproductive success.

Male Characteristics and Pairing Success in Red-Winged Blackbirds

The Auk ◽  
1979 ◽  
Vol 96 (2) ◽  
pp. 353-363 ◽  
Author(s):  
William A. Searcy
Keyword(s):  
Site Fidelity ◽  
Competitive Ability ◽  
Optimal Choice ◽  
Agelaius Phoeniceus ◽  
Strong Correlations ◽  
Territory Quality ◽  
Large Size ◽  
Harem Size ◽  
Weak Evidence ◽  
Experience Good

Abstract As female Red-winged Blackbirds (Agelaius phoeniceus) in Washington populations choose mates mainly on the basis of territory quality, sexual selection should favor those characteristics that enhance a male redwing's ability to obtain and defend a good territory. In this study, correlations were sought between harem size and characteristics of male redwings that might be expected to contribute to the ability to compete for territory. Weak evidence is presented that large size, experience, good physiological condition, and the ability to devote a large proportion of daily activity to territory defense contribute to pairing success in some years. Even the significant correlations between success and male characteristics are weak, but strong correlations cannot be expected because (1) many different male characteristics probably contribute to competitive ability, none of which are of overwhelming importance; (2) males will not always make the optimal choice of territory, especially as their choice is constrained by extreme site fidelity; and (3) females will also fail to make optimal choices of territories and mates.

Reproductive success is a misleading indicator of nest-site preferences in the Red-winged Blackbird

1998 ◽  
Vol 76 (12) ◽  
pp. 2227-2234 ◽  
Author(s):  
Stanislav Pribil
Keyword(s):  
Reproductive Success ◽  
Site Selection ◽  
Nest Site ◽  
Nest Site Selection ◽  
Agelaius Phoeniceus ◽  
Erroneous Conclusion ◽  
Nest Sites ◽  
Site Preferences ◽  
Limited Variation ◽  
Nest Site Preferences

Several methods are used to detect nest-site preferences of birds. One method postulates that individuals will prefer those nest-site features that increase their reproductive success. To determine which features affect reproductive success, and hence should be preferred, the method examines correlations between reproductive success and various nest-site features. When a statistically significant correlation is found, it is concluded that individuals exhibit a preference for that feature. In the absence of a correlation, it is concluded that individuals are indifferent to the feature. Here, I argue that this method may lead to misleading conclusions. If good sites are abundant, all individuals should choose them. Consequently, there will be little variation in the features of the chosen sites. This limited variation, when related to reproductive success, may fail to yield a statistically significant correlation and thus lead to the erroneous conclusion that individuals have no preference. An alternative method of detecting nest-site preferences is to compare features of chosen sites with features of available sites. In this study, I used both methods to investigate nest-site selection in the Red-winged Blackbird (Agelaius phoeniceus). I compared vegetation features of nest sites with those of randomly selected sampling sites and found significant differences. The differences imply that Red-winged Blackbirds prefer vegetation that grows in small patches and is tall and sparse, and the plants have thick stems. I found no relationship between these vegetation features and reproductive success. These results suggest that Red-winged Blackbirds have strong preferences for certain vegetation features, but these preferences cannot be detected from correlations with reproductive success.

Female Choice in Middendorff's Grasshopper-Warbler (Locustella Ochotensis)

The Auk ◽  
1986 ◽  
Vol 103 (4) ◽  
pp. 694-700 ◽  
Author(s):  
Hisashi Nagata
Keyword(s):  
Mate Choice ◽  
Female Choice ◽  
Morphological Characteristics ◽  
Female Mate Choice ◽  
Food Abundance ◽  
Territory Size ◽  
Territory Quality ◽  
Female Mate ◽  
Nest Sites ◽  
Grasshopper Warbler

Abstract Morphological and territorial factors that influence female mate choice were examined in the monogamous Middendorff's Grasshopper-Warbler (Locustella ochotensis) on an islet near Fukuoka, Japan. I assumed that pairing date corresponded with female mate choice. Pairing date was correlated with both territory size and food abundance but was not correlated with selected morphological characteristics of males. Territorial quality was assumed to be correlated with territory size because preferable food resources and nest sites were distributed randomly. I conclude that female mate choice was influenced by territory quality rather than by the morphological characteristics of males.

Association of Weather and Nest-Site Structure with Reproductive Success in California Spotted Owls

2000 ◽  
Vol 64 (3) ◽  
pp. 797 ◽  
Author(s):  
Malcolm North ◽  
George Steger ◽  
Renee Denton ◽  
Gary Eberlein ◽  
Tom Munton ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Nest Site ◽  
Site Structure ◽  
Spotted Owls

Laboratory comparison of the relative success of Biomphalaria glabrata stocks which are susceptible and insusceptible to infection with Schistosoma mansoni

Parasitology ◽  
1983 ◽  
Vol 86 (2) ◽  
pp. 335-344 ◽  
Author(s):  
D. J. Minchella ◽  
P. T. Loverde
Keyword(s):  
Life Cycle ◽  
Natural Selection ◽  
Reproductive Success ◽  
Natural Populations ◽  
Biomphalaria Glabrata ◽  
Selective Advantage ◽  
Controlled Conditions ◽  
Plausible Answer ◽  
Major Objection ◽  
Transmit Disease

SUMMARYA method of interrupting the life-cycle of the human blood fluke Schistosoma by increasing the proportion of genetically insusceptible intermediate host snails in natural populations was first proposed nearly 25 years ago. The method assumes that insusceptible snails will be at a selective advantage over susceptible snails when the schistosome parasite is present, and therefore natural selection will act to increase the proportion of alleles for insusceptibility. A major objection to the proposed technique is ‘If insusceptible snails are at a selective advantage, then why are they not predominant in natural populations that transmit disease?’ One explanation of this paradox is that insusceptibility may be associated with a disadvantageous character or a physiological defect. This study tests this hypothesis by measuring the relative reproductive success of susceptible and insusceptible snails under controlled conditions. Results indicate that insusceptible (unsuitable) snails are negatively affected in the presence of either susceptible snails or schistosome parasites. Furthermore, in the presence of both susceptible snails and schistosome parasites, insusceptible snails are selectively disadvantaged compared to susceptible snails. These results obtained under laboratory-controlled conditions suggest a plausible answer as to why insusceptible snails are not predominant in natural populations that transmit disease.

scholarly journals Breeding of the common kingfisher Alcedo atthis at the Boracka River

2016 ◽  
pp. 105-112 ◽  
Author(s):  
Ivana Novcic
Keyword(s):  
Breeding Season ◽  
Riparian Vegetation ◽  
Breeding Population ◽  
Stream Habitat ◽  
Breeding Density ◽  
The Common

The breeding population of the common kingfisher Alcedo atthis was studied in the Boracka River area in 2006 and 2007. A high breeding density was docu?mented in 2007 with five breeding pairs recorded along the 1.4 km section of a stream habitat. All of the studied nests were placed in vertical banks without excessive riparian vegetation, while the distance between adjacent nests ranged 120-430 m. The same nest holes were used in both years, although birds excavated a couple of new ones in 2007. One pair bred in two consecutive years; the same pair had two breeding attempts in 2007, while three breeding attempts were recorded for one male. Birds used the same holes for subsequent clutches or excavated new nests. Also, one nest was used by different pairs in the same breeding season. In the study period 21 individuals were banded - none of the juvenile in?dividuals was recaptured, suggesting that the fledglings dispersed shortly after they had left their nests. Also, none of the breeding individuals was recaptured at the river outside the breeding season.

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