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Cooperative breeding (i.e. when alloparents care for the offspring of other group members) has been studied for nearly a century. Yet, inconsistent definitions of this breeding system still hamper comparative research. Here, we identify two major inconsistencies, discuss their consequences and propose a way forward. First, some researchers restrict the term 'cooperative breeding' to species with non‐breeding alloparents. We show that such restrictive definitions lack distinct quantitative criteria to define non‐breeding alloparents. This ambiguity, we argue, reflects the reproductive‐sharing continuum among cooperatively breeding species. We therefore suggest that cooperative breeding should not be restricted to the few species with extreme reproductive skew and should be defined independent of the reproductive status of alloparents. Second, definitions rarely specify the type, extent and prevalence of alloparental care required to classify species as cooperative breeders. We thus analysed published data to propose qualitative and quantitative criteria for alloparental care. We conclude by proposing the following operational definition: cooperative breeding is a reproductive system where >5% of broods/litters in at least one population receive species‐typical parental care and conspecifics provide proactive alloparental care that fulfils >5% of at least one type of the offspring's needs. This operational definition is designed to increase comparability across species and disciplines while allowing to study the intriguing phenomenon of cooperative breeding as a behaviour with multiple dimensions. [ABSTRACT FROM AUTHOR]

Pollutants as endocrine disrupting chemicals (EDCs) are of worldwide concern, due to their detrimental effects on the physiology and behaviour of wildlife. One major source of EDCs is sewage treatment works which serve as foraging grounds for many bird species. However, the risks of consuming EDCs to wild birds at these sites have been largely overlooked. We have previously quantified contamination levels of invertebrates from within filter beds of sewage treatment works and the intake rates of these invertebrates by wild European starlings feeding at these sites. Our work to date has shown that environmentally-relevant EDC exposure results in reduced immunocompetence, increased song behaviour and neural development in adult starlings. In the present study, we hypothesized that nestling starlings exposed to similar EDC levels from contaminated prey, from parental feeding at sewage treatment works, would show altered growth and physiology. Our findings show that EDC exposure results in reduced growth and immunocompetence in nestling birds. However, there was no effect on corticosterone or haematocrit levels. As growth rates and immunocompetence are likely to be related to survival rates, we suggest that these exposure levels are likely to adversely affect recruitment into the adult population. Synthesis and applications. These results highlight the potential transfer of EDCs between semi-aquatic or aquatic organisms and terrestrial organisms up the food chain at sites of sewage treatment works, broadening the scope of potential routes of exposure. Our findings suggest that birds foraging in these sites are at risk of physiological manipulation from EDCs and reduced body condition as a result. We advocate further work to evaluate the potential for EDCs from sewage treatment works to bioaccumulate and modulate the condition of wild organisms feeding on contaminated prey. Our results suggest that changes in management practices of sewage treatment works are required. We support measures to reduce EDC levels in sewage treatment works and that these sites should be designed to exclude or deter wildlife from foraging on contaminated prey. The management implications of such policy - oriented steps will ensure the health of wildlife foraging at sewage treatment works. [ABSTRACT FROM AUTHOR]

Ecology Letters (2010) 13: 1129–1138 Prey species commonly use predator-released kairomones (PRKs) to detect risk of predation, yet the chemical identity of PRKs remains elusive. Chemical identification of PRKs will facilitate the study of predator–prey interactions and the risk of predation, and when the prey are pests, will potentially provide environmentally friendly means of pest control. In temporary pools of the Mediterranean and Middle East, larvae of the mosquito Culiseta longiareolata Macquart are highly vulnerable to the common predatory backswimmer, Notonecta maculata Fabricius. We demonstrate that N. maculata releases two hydrocarbons, n-heneicosane and n-tricosane, which repel ovipositing females of C. longiareolata. In behavioural tests with environmentally relevant chemical concentrations in outdoor mesocosm experiments, the repellent effects of the two compounds were additive at the tested concentrations. [ABSTRACT FROM AUTHOR]

The timing of the chick-rearing phase is known to have a profound effect on the reproductive success of birds. However, little is known about the energetic costs faced by the parents during different periods of the breeding season. These costs may have vital consequences for both their survival and future reproduction. In most studies, daily energy expenditure (DEE) of breeding and non-breeding birds has been compared, without controlling for the effect of season. In the present study, we examined the energy demands of breeding compared to non-breeding Palestine sunbirds Nectarinia osea and whether there were sex-specific differences in DEE within and between different seasons. We predicted that DEE would be elevated when birds rear chicks, especially at cooler ambient temperatures. Time-energy budgets were constructed for pairs of sunbirds, rearing chicks, or not breeding, in spring and summer. There were significant seasonal differences in estimates of DEE in non-breeders that were 21% higher in spring than in summer. We attributed these to increases in non-flight metabolic rate rather than changes in time spent on different activities. Our estimates of DEE for the birds that were rearing chicks were higher than non-breeding adults. In females the increase in DEE when breeding, compared to when not breeding, was similar in both spring and summer, while males increased their DEE much less when breeding in spring. The differences in estimated DEE, however, were not significant between male and female birds in any season. Between seasons, female breeders had 17.1% higher DEE in spring than in summer, while male breeders showed no difference in DEE when rearing chicks in different seasons. Accordingly, our initial prediction was supported, as DEE in chick-rearing adults was higher than in non-breeding adults. In addition, although temperatures are lower in spring, breeding in the spring is only more costly than breeding in summer for females. Apparently, males are more flexible in reallocating their time and energy spent on different activities. [ABSTRACT FROM AUTHOR]

Despite its importance in the evolution of central-place foraging strategies, few studies have distinguished between patch use by parent birds for their own consumption vs. patch use for the purpose of provisioning young in the nest. Adult Palestine sunbirds (Nectarinia osea) consume nectar and arthropods, but feed only arthropods to their nestlings. This partial separation of food types allowed us to experimentally test sex-specific trade-offs in parental foraging effort between two patches. A ‘variable’ patch on one side of a pair's territory contained only artificial nectar for parental self-feeding (in varying sucrose concentrations between 0·25 and 0·75 mol kg&sup-1; H2O). A ‘constant’ patch on the other side of the territory contained artificial nectar for parental self-feeding (sucrose concentration = 0·25 mol kg&sup-1; H2O), plus a dish of flightless houseflies for provisioning young. Experimental increases in sucrose concentration in the variable patch led the parents to: (a) consume greater amounts of sucrose solution from this patch; (b) collect more flies from the constant patch to feed their young; and (c) persistently use the 0·25 mol kg&sup-1; H2O feeder near the dish of flies. By titration (gradually changing the sucrose concentration in the variable patch), we demonstrate that at concentrations of 0·47 mol kg&sup-1; H2O for males and 0·55 mol kg&sup-1; H2O for females, the birds spent an equal amount of time foraging in both patches. Therefore, sucrose concentration in the variable patch (for self-feeding only), had to be higher for the females than for the males, in order to balance the additional value females placed upon the flies provided for chick-feeding in the constant patch. These results reflect previously described sex-specific parental roles in this species, with females provisioning young mainly in the nest and males patrolling more and guarding against nest predators. Furthermore, we demonstrate for the first time the fine details of alternative adaptive trade-offs in foraging effort by parent birds when using patches for self-feeding or for delivery of food to the young. [ABSTRACT FROM AUTHOR]