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Cooperative Breeders (cooperative + breeder)
Selected AbstractsDivorce, dispersal and incest avoidance in the cooperatively breeding superb fairy-wren Malurus cyaneusJOURNAL OF ANIMAL ECOLOGY, Issue 2 2003Andrew Cockburn Summary 1Between 1988 and 2001, we studied social relationships in the superb fairy-wren Malurus cyaneus (Latham), a cooperative breeder with male helpers in which extra-group fertilizations are more common than within-pair fertilizations. 2Unlike other fairy-wren species, females never bred on their natal territory. First-year females dispersed either directly from their natal territory to a breeding vacancy or to a foreign ,staging-post' territory where they spent their first winter as a subordinate. Females dispersing to a foreign territory settled in larger groups. Females on foreign territories inherited the territory if the dominant female died, and were sometimes able to split the territory into two by pairing with a helper male. However, most dispersed again to obtain a vacancy. 3Females dispersing from a staging post usually gained a neighbouring vacancy, but females gaining a vacancy directly from their natal territory travelled further, perhaps to avoid pairing or mating with related males. 4Females frequently divorced their partner, although the majority of relationships were terminated by the death of one of the pair. If death did not intervene, one-third of pairings were terminated by female-initiated divorce within 1000 days. 5Three divorce syndromes were recognized. First, females that failed to obtain a preferred territory moved to territories with more helpers. Secondly, females that became paired to their sons when their partner died usually divorced away from them. Thirdly, females that have been in a long relationship divorce once a son has gained the senior helper position. 6Dispersal to avoid pairing with sons is consistent with incest avoidance. However, there may be two additional benefits. Mothers do not mate with their sons, so dispersal by the mother liberates her sons to compete for within-group matings. Further, divorcing once their son has become a breeder or a senior helper allows the female to start sons in a queue for dominance on another territory. Females that do not take this option face constraints on their ability to recruit more sons into the local neighbourhood. [source] Observations on the breeding behaviour of the Stripe-breasted tit (Parus fasciiventer) in Bwindi Impenetrable National Park, UgandaAFRICAN JOURNAL OF ECOLOGY, Issue 2 2010Jane Yatuha Abstract The motivation of this study was to investigate some hitherto unknown information on the breeding ecology of the Stripe-breasted Tit (Parus fasciiventer) in Bwindi Impenetrable National Park, south-western Uganda. Parus fasciiventer is one of the least studied and endemic bird species restricted to the montane forests of the Albertine Rift. Regionally, it is classified as near-threatened. The study was carried out around the Institute of Tropical Forest Conservation Ruhija camp and the period of study was from January to June 2003. Data were generated through direct observation at the nest box sites of three active nests. Each of the nest boxes was monitored from the time of nest building to the time the chicks fledged. Results and comparative assessments from this study demonstrate that P. fasciiventer, compared with its temperate congeners like Great Tits (Parus major), Marsh Tits (Parus palustris), Crested Tits (Parus cristatus), Coal Tits (Parus ater) and Blue Tits (Parus caeruleus), raised small broods and had longer nestling period. The findings further revealed that the species is capable of raising more than one brood in a single breeding season and provide further evidence that it is a cooperative breeder. Parents participated equally in raising the young, an indication of pure parenting in the species. Résumé La raison de cette étude était de rechercher certaines informations jusqu'alors inconnues sur l'écologie de la reproduction de la mésange à ventre strié, Parus fasciiventer, dans le Parc National de la Forêt impénétrable de Bwindi, dans le sud-ouest de l'Ouganda. Parus fasciiventer est une des espèces d'oiseaux endémiques les moins étudiées; elle se limite aux forêts de montagne du Rift Albertin. Au niveau régional, elle est classée comme quasi menacée. L'étude s'est réalisée autour du camp de Ruhija de l'Institute of Tropical Forest Conservation de janvier à juin 2003. Les données furent obtenues par des observations directes sur les sites de trois nichoirs actifs. Chaque nid a été suivi depuis sa construction jusqu'à la mue des oisillons. Les résultats et des évaluations comparatives de cette étude ont montré que P. fasciiventer, comparéà ses congénères des régions tempérées comme la mésange charbonnière Parus major, la mésange nonnette Parus palustris, la mésange huppée Parus cristatus, la mésange noire Parus ater et la mésange bleue Parus caeruleus, élevait de plus petites nichées et avait une plus longue durée de nidification. Les résultats ont aussi révélé que cette espèce est capable d'élever plus d'une nichée au cours d'une même saison de reproduction et apportent de nouvelles preuves du fait que c'est une espèce qui pratique la reproduction coopérative. Les parents participaient de façon équitable à l'élevage des jeunes, un signe de parenté directe chez cette espèce. [source] Reproductive success and helper effects in the cooperatively breeding grey-crowned babblerJOURNAL OF ZOOLOGY, Issue 3 2007C. J. Blackmore Abstract Cooperative breeding, where some individuals help to raise offspring that are not their own, is a relatively rare social system in birds. We studied the breeding biology of a declining cooperative breeder, the grey-crowned babbler Pomatostomus temporalis, with the aim of isolating the social factors that affect its reproductive success. Most breeding pairs were assisted by philopatric offspring, although pairs could breed successfully without helpers. Females laid up to four clutches (usually three eggs per clutch) per season. Male (but not female) helpers increased the number of young fledged from individual nests and the likelihood of re-nesting, resulting in higher seasonal fledgling production. Helper effects on brood size and fledgling production were greater in the second year of the study, which was also characterized by higher nest failure. This suggests that helpers enhance reproduction more in poor conditions. Our study demonstrates the interacting effects of social and ecological factors on reproductive success, and that retention of offspring is not always beneficial for the breeders in cooperative species. [source] Female-Biased Helping in a Cooperatively Breeding Bird: Female Benefits or Male Costs?ETHOLOGY, Issue 6 2007Dean A. Williams There is often a sex bias in helping effort in cooperatively breeding species with both male and female helpers, and yet this phenomenon is still poorly understood. Although sex-biased helping is often assumed to be correlated with sex-specific benefits, sex-specific costs could also be responsible for sex-biased helping. Cooperatively breeding brown jays (Cyanocorax morio) in Monteverde, Costa Rica have helpers of both sexes and dispersal is male-biased, a rare reversal of the female-biased dispersal pattern often seen in birds. We quantified helper contributions to nestling care and analyzed whether there was sex-biased helping and if so, whether it was correlated with known benefits derived via helping. Brown jay helpers provided over 70% of all nestling feedings, but they did not appear to decrease the workload of breeders across the range of observed group sizes. Female helpers fed nestlings and engaged in vigilance at significantly higher levels than male helpers. Nonetheless, female helpers did not appear to gain direct benefits, either through current reproduction or group augmentation, or indirect fitness benefits from helping during the nestling stage. While it is possible that females could be accruing subtle future direct benefits such as breeding experience or alliance formation from helping, future studies should focus on whether the observed sex bias in helping is because males decrease their care relative to females in order to pursue extra-territorial forays. Explanations for sex-biased helping in cooperative breeders are proving to be as varied as those proposed for helping behavior in general, suggesting that it will often be necessary to quantify a wide range of benefits and costs when seeking explanations for sex-biased helping. [source] Singing in the Face of Danger: the Anomalous Type II Vocalization of the Splendid Fairy-WrenETHOLOGY, Issue 3 2001Bethanne Zelano Males of certain species of fairy-wrens (Aves: Maluridae) emit a unique vocalization, the Type II vocalization, in response to the calls of potential predators. We conducted field observations and playback experiments to identify the contexts in which the Type II vocalization is emitted by splendid fairy-wren (Malurus splendens) males, and to examine social and genetic factors that influence its occurrence. In field observations and controlled playback experiments, Type II vocalizations were elicited most consistently by calls of the predatory gray butcherbird (Cracticus torquatus). Some vocalizations from other avian species also elicited Type II vocalizations, and the majority of these were vocalizations from avian predators. Splendid fairy-wrens are cooperative breeders, and males that responded with Type II vocalizations to playbacks of butcherbird calls tended to be primary rather than secondary males, had larger cloacal protuberances, and were older than those that did not respond. In addition, secondary males that were sons of resident females were more likely than non-sons to respond with a Type II vocalization. In another playback experiment, females responded similarly to the Type I song and Type II vocalizations of their mates. Although the Type II vocalization is emitted primarily in response to predator calls, it is inconsistent with an alarm call explanation. Patterns of reproductive success among Type II calling males suggest that it does not function as an honest signal of male quality. At present, the function of the vocalization remains anomalous, but indirect fitness benefits may play a role in its explanation. [source] Social organization of cooperatively breeding long-tailed tits: kinship and spatial dynamicsJOURNAL OF ANIMAL ECOLOGY, Issue 5 2001B. J. Hatchwell Summary 1Long-tailed tits Aegithalos caudatus L. are cooperative breeders in which breeders that have failed in their own breeding attempt become helpers at the nest of relatives. We investigated the effects of kinship on the spatial dynamics of non-breeding flocks of long-tailed tits in order to determine the information available on the kinship of other members of the population from their use of home ranges. 2A novel method of home range analysis was devised based on ,convex hull peeling'. This method takes into account the dispersion of all fixes within a home range and permits the quantitative analysis of home range use. In addition, the method allows the extent of overlap between adjacent home ranges to be determined and the use of those areas to be investigated. 3Non-breeding flocks of long-tailed tits were composed mainly of relatives, but also included unrelated immigrants. Flock ranges were large and there was extensive overlap between adjacent flocks. 4The degree of range overlap was significantly affected by the relatedness of flocks. If two flocks contained close relatives they were more likely to overlap than two flocks containing non-relatives. Moreover, the amount of overlap was significantly greater for two adjacent related flocks than for two adjacent unrelated flocks. 5The use of overlapping areas of non-breeding ranges of long-tailed tit flocks was also influenced significantly by relatedness. Overlapping flocks that were unrelated to each other usually avoided areas of overlap, while related flocks did not generally show such avoidance behaviour. 6Kinship has significant effects on the spatial dynamics of non-breeding flocks of long-tailed tits and therefore flock behaviour can provide information on the relatedness of other members of the population that might be important for helping decisions in this cooperatively breeding species. [source] Implications of mitochondrial DNA polyphyly in two ecologically undifferentiated but morphologically distinct migratory birds, the masked and white-browed woodswallows Artamus spp. of inland AustraliaJOURNAL OF AVIAN BIOLOGY, Issue 6 2006Leo Joseph The white-browed woodswallow Artamus superciliosus and masked woodswallow A. personatus (Passeriformes: Artamidae) are members of Australia's diverse arid- and semi-arid zone avifauna. Widely sympatric and among Australia's relatively few obligate long-distance temperate-tropical migrants, the two are well differentiated morphologically but not ecologically and vocally. They are pair breeders unlike other Artamus species, which are at least facultative cooperative breeders. For these reasons they are an excellent case in which to use molecular data in integrative study of their evolution from ecological and biogeographical perspectives. We used mitochondrial DNA (mtDNA) to test whether they are each other's closest relatives, whether they evolved migration independently, whether they have molecular signatures of population expansions like some other Australian arid zone birds, and to estimate the timing of any inferred population expansions. Their mtDNAs are monophyletic with respect to other species of Artamus but polyphyletic with respect to each other. The two species appear not to have evolved migration independently of each other but their morphological and mtDNA evolution have been strongly decoupled. Some level of hybridization and introgression cannot be dismissed outright as being involved in their mtDNA polyphyly but incomplete sorting of their most recent common ancestor's mtDNA is a simpler explanation consistent with their ecology. Bayesian phylogenetic inference and analyses of diversity within the two species (n=77) with conventional diversity statistics, statistical parsimony, and tests for population expansion vs stability (Tajima's D, Fu's Fs and Ramos-Onsin and Rozas's R2) all favour recent population increases. However, a non-starlike network suggests expansion(s) relatively early in the Pleistocene. Repeated population bottlenecks corresponding with multiple peaks of Pleistocene aridity could explain our findings, which add a new dimension to accruing data on the effects of Pleistocene aridity on the Australian biota. [source] | ||||||||||