Open Access. Powered by Scholars. Published by Universities.®
- Discipline
Articles 1 - 9 of 9
Full-Text Articles in Life Sciences
Territory Inheritance And The Evolution Of Cooperative Breeding In The Acorn Woodpecker, Walter D. Koenig, Joseph Haydock, Hannah L. Dugdale, Eric L. Walters
Territory Inheritance And The Evolution Of Cooperative Breeding In The Acorn Woodpecker, Walter D. Koenig, Joseph Haydock, Hannah L. Dugdale, Eric L. Walters
Biological Sciences Faculty Publications
There are two main hypotheses for why offspring in cooperatively breeding taxa delay dispersal and remain on their natal territory rather than disperse. First, ecological constraints may force offspring to remain on their natal territory until a reproductive opportunity presents itself in an otherwise saturated habitat. Alternatively, delaying dispersal and helping kin may increase an offspring's inclusive fitness. One means by which offspring might enhance their direct fitness by delaying dispersal is by inheriting breeding status on their natal territory. Such territory inheritance regularly occurs in acorn woodpeckers, Melanerpes formicivorus, a species whose social groups consist of a cooperatively …
Lifetime Inclusive Fitness Effects Of Cooperative Polygamy In The Acorn Woodpecker, Walter D. Koenig, Sahas Barve, Joseph Haydock, Eric L. Walters
Lifetime Inclusive Fitness Effects Of Cooperative Polygamy In The Acorn Woodpecker, Walter D. Koenig, Sahas Barve, Joseph Haydock, Eric L. Walters
Biological Sciences Faculty Publications
Although over 50 y have passed since W. D. Hamilton articulated kin selection and inclusive fitness as evolutionary explanations for altruistic behavior, quantifying inclusive fitness continues to be challenging. Here, using 30 y of data and two alternative methods, we outline an approach to measure lifetime inclusive fitness effects of cooperative polygamy (mate-sharing or cobreeding) in the cooperatively breeding acorn woodpecker Melanerpes formicivorus. For both sexes, the number of offspring (observed direct fitness) declined while the number of young parented by related cobreeders (observed indirect fitness effect) increased with cobreeding coalition size. Combining these two factors, the observed inclusive …
Lifetime Reproductive Benefits Of Cooperative Polygamy Vary For Males And Females In The Acorn Woodpecker (Melanerpes Formicivorus), Sahas Barve, Christina Riehl, Eric L. Walters, Joseph Haydock, Hannah L. Dugdale, Walter D. Koenig
Lifetime Reproductive Benefits Of Cooperative Polygamy Vary For Males And Females In The Acorn Woodpecker (Melanerpes Formicivorus), Sahas Barve, Christina Riehl, Eric L. Walters, Joseph Haydock, Hannah L. Dugdale, Walter D. Koenig
Biological Sciences Faculty Publications
Cooperative breeding strategies lead to short-term direct fitness losses when individuals forfeit or share reproduction. The direct fitness benefits of cooperative strategies are often delayed and difficult to quantify, requiring data on lifetime reproduction. Here, we use a longitudinal dataset to examine the lifetime reproductive success of cooperative polygamy in acorn woodpeckers (Melanerpes formicivorus), which nest as lone pairs or share reproduction with same-sex cobreeders. We found that males and females produced fewer young per successful nesting attempt when sharing reproduction. However, males nesting in duos and trios had longer reproductive lifespans, more lifetime nesting attempts and higher …
Wandering Woodpeckers: Foray Behavior In A Social Bird, Sahas Barve, Natasha D. G. Hagemeyer, Russell E. Winter, Samuel D. Chamberlain, Walter D. Koenig, David W. Winkler, Eric L. Walters
Wandering Woodpeckers: Foray Behavior In A Social Bird, Sahas Barve, Natasha D. G. Hagemeyer, Russell E. Winter, Samuel D. Chamberlain, Walter D. Koenig, David W. Winkler, Eric L. Walters
Biological Sciences Faculty Publications
In many cooperatively breeding taxa, nonbreeding subordinates, or helpers, use extra-territorial forays to discover dispersal opportunities. Such forays are considered energetically costly and foraying birds face aggression from conspecific members of the territories they visit. In contrast, breeders in cooperatively breeding taxa are expected to foray seldomly. We used novel tracking technologies to follow 62 acorn woodpeckers (Melanerpes formicivorus), a cooperatively breeding bird, to study extra-territorial foray behavior. Both helpers and breeders engaged in extra-territorial forays routinely and often several times per day. Helpers forayed earlier in the day and invested more time when foraying to high-quality territories. …
Does Helping-At-The-Nest Help? The Case Of The Acorn Woodpecker, Walter D. Koenig, Eric L. Walters, Sahas Barve
Does Helping-At-The-Nest Help? The Case Of The Acorn Woodpecker, Walter D. Koenig, Eric L. Walters, Sahas Barve
Biological Sciences Faculty Publications
Cooperative breeding groups often involve "helpers-at-the-nest"; indeed, such behavior typically defines this intriguing breeding system. In few cases, however, has it been demonstrated that feeding nestlings by helpers, rather than some other behavior associated with helpers' presence, leads to greater reproductive success. One prediction of the hypothesis that feeding behavior per se is responsible for the fitness benefits conferred by helpers is that there should be close congruence between the patterns of helping-at-the-nest and the fitness effects of helpers. Here we look for such a relationship in the cooperatively breeding acorn woodpecker (Melanerpes formicivorus) in order to begin …
Habitat Saturation Results In Joint-Nesting Female Coalitions In A Social Bird, Sahas Barve, Walter D. Koenig, Joseph Haydock, Eric L. Walters
Habitat Saturation Results In Joint-Nesting Female Coalitions In A Social Bird, Sahas Barve, Walter D. Koenig, Joseph Haydock, Eric L. Walters
Biological Sciences Faculty Publications
Joint nesting by females and cooperative polyandry—cooperatively breeding groups with a male-biased breeder sex ratio—are little-understood, rare breeding systems. We tested alternative hypotheses of factors potentially driving these phenomena in a population of joint-nesting acorn woodpeckers (Melanerpes formicivorus). During periods of high population density and thus low independent breeding opportunities, acorn woodpecker females formed joint-nesting coalitions with close kin. Coalitions were typically associated with groups with a male bias. We found strong evidence for both inter- and intrasexual conflict, as joint nesting conferred a fitness benefit to some males, a significant fitness cost to females, and no gain in per …
Temporal Variability And Cooperative Breeding: Testing The Bet-Hedging Hypothesis In The Acorn Woodpecker, Walter D. Koenig, Eric L. Walters
Temporal Variability And Cooperative Breeding: Testing The Bet-Hedging Hypothesis In The Acorn Woodpecker, Walter D. Koenig, Eric L. Walters
Biological Sciences Faculty Publications
Cooperative breeding is generally considered an adaptation to ecological constraints on dispersal and independent breeding, usually due to limited breeding opportunities. Although benefits of cooperative breeding are typically thought of in terms of increased mean reproductive success, it has recently been proposed that this phenomenonmay be a bet-hedging strategy that reduces variance in reproductive success (fecundity variance) inpopulations living inhighly variable environments. We tested this hypothesis using long-term data on the polygynandrous acorn woodpecker (Melanerpes formicivorus). In general, fecundity variance decreased with increasing sociality, at least when controlling for annual variation in ecological conditions. Nonetheless, decreased fecundity variance …
Brooding, Provisioning, And Compensatory Care In The Cooperatively Breeding Acorn Woodpecker, Walter D. Koenig, Eric L. Walters
Brooding, Provisioning, And Compensatory Care In The Cooperatively Breeding Acorn Woodpecker, Walter D. Koenig, Eric L. Walters
Biological Sciences Faculty Publications
We analyzed reproductive investment in parental care (brooding and the provisioning of nestlings) in the acorn woodpecker (Melanerpes formicivorus), a cooperatively breeding species in which both polygynandry and helping-at-the-nest are common. As predicted based on the strategies pursued by birds of different sex and status, breeders generally invested more in parental care than helpers, and breeder females invested more than breeder males. Contrary to expectations, however, the degree to which individuals reduced their effort with increasing group size (i.e., patterns of load lightening or compensatory care) did not match overall investment. Instead, as group size increased, there was …
Variable Helper Effects, Ecological Conditions, And The Evolution Of Cooperative Breeding In The Acorn Woodpecker, Walter D. Koenig, Eric L. Walters, Joseph Haydock
Variable Helper Effects, Ecological Conditions, And The Evolution Of Cooperative Breeding In The Acorn Woodpecker, Walter D. Koenig, Eric L. Walters, Joseph Haydock
Biological Sciences Faculty Publications
The ecological conditions leading to delayed dispersal and helping behavior are generally thought to follow one of two contrasting scenarios: that conditions are stable and predictable, resulting in young being ecologically forced to remain as helpers (extrinsic constraints and the habitat saturation hypothesis), or that conditions are highly variable and unpredictable, leading to the need for helpers to raise young, at least when conditions are poor (intrinsic constraints and the hard life hypothesis). We investigated how variability in ecological conditions influences the degree to which helpers augment breeder fitness in the cooperatively breeding acorn woodpecker (Melanerpes formicivorus), a …