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Global urbanization processes have highlighted the importance of understanding the effects of urban habitats on animal behavior. Behavioral changes are usually evaluated along an urbanization gradient, comparing urban and rural populations. However, this metric fails to consider heterogeneity between urban habitats that can differ significantly in their characteristics, such as their level of environmental variability. We suggest incorporating dimensions of environmental variability into the urbanization metric when evaluating behavioral changes. We tested the importance of both level of urbanization and level of urban change (i.e. the rate of anthropogenic changes measured as the change in the level of urbanization over time) on animals' behavioral flexibility by comparing reversal learning abilities in house sparrows from sites differing in the rate of urbanization and urban change levels. We show that at least for males, urban change better explains levels of behavioral flexibility than urbanization level. We further show that urban change corresponds to other behavioral traits such as scrounging behavior and foraging activity. Thus, considering environmental stability and predictability in the form of urban changes can help better understand the mechanisms allowing behavioral changes and adaptations to urban environments. Evaluating the dynamics of the urban built environment could provide a better metric with which to understand urbanization effects on wildlife behavior and an important next step in urban ecology. [ABSTRACT FROM AUTHOR]

Differences between individuals in correlated responses across contexts have both functional and mechanistic implications. Such syndromes may have either beneficial or harmful consequences when novel changes in the environment occur. We used wild-caught house sparrows, Passer domesticus, to test in functionally relevant circumstances, whether neophobia (initial fear of novelty), habituation, and the learning of novel cues (discriminant learning) were linked by a common underlying mechanism or reflected separate processes. We repeatedly measured individual latencies to approach and also to feed from a familiar feeding site in 3 contexts: a baseline control for mild disturbance, in the presence of a novel object and to a novel cue indicating hidden food. House sparrows on average exhibited neophobia, habituated to novel objects, and learned to associate new cues with a reward. We also found evidence for consistent individual differences in both latencies within most contexts but there was no evidence of individual differences in plasticity with repeated trials within either the novel object (habituation) or novel cue (learning) contexts. There was also little or no correlation between the 2 latencies within individuals within contexts. Individual differences in latencies to arrive at the food station exhibited strong correlations across contexts but latencies to feed were weaker. These results suggest a personality trait that exists regardless of novelty but no syndrome affecting reactions to different forms of novelty. House sparrows appear strongly plastic when responding to novel environments. Such plasticity is likely favored by the varied consequences of novelty across environments. [ABSTRACT FROM AUTHOR]

Over the last century, expanding urbanization has led to a strong increase in the levels of background noise. This noise pollution has been shown to negatively affect wildlife (e.g., reduced species diversity and density, reduced breeding success), especially birds. Most research addressing the effects of anthropogenic noise has focused on avian communication and, to date, very little is known regarding the impact of chronic noise exposure on nonvocal behavior such as antipredator behavior. Here, we exposed free-living house sparrows (Passer domesticus) breeding in nest-boxes to either a playback of traffic noise (disturbed birds) or the rural background noise of the study site (no playback: control birds) during their first breeding attempt. We tested whether one of the female's antipredator behaviors (i.e., flushing distance) was affected by exposure to chronic noise and investigated the impact of chronic noise on reproductive performances. Disturbed females flushed more rapidly than controls, suggesting that birds may compensate for reduced ability to detect predators with increased vigilance. However, we found no significant effect of exposure to chronic noise on reproductive performances. Our findings show, for the first time, that chronic noise exposure can affect the antipredator behavior of a breeding bird. [ABSTRACT FROM AUTHOR]

Males frequently signal their resistance against parasites by elaborate ornaments. By mating with more ornamented males, females may choose less parasitized partners, and benefit by reducing the probability of contagion of parasites with direct transmission. Chewing lice (order Phthiraptera) are parasites of birds that considerably harm hosts, even decreasing survival. Previous studies showed that male house sparrows (Passer domesticus) can signal resistance against chewing lice by the size of the white wing bar, with more resistant birds having a larger bar. Here, in a mate-choice experiment, 16 female sparrows were presented to 16 dyads of males having similar initial wing bar sizes. In each dyad, the wing bar was experimentally reduced in a randomly selected male. Female house sparrows chose males with larger wing bars. Nevertheless, females also preferred males with less feather holes caused by chewing lice and larger males. By choosing males with larger wing bars, females choose males with larger uropygial glands, an organ involved in the resistance against chewing lice in this species. Therefore, white patches, which are widespread in birds, might be used by females in order to evaluate male resistance against chewing lice. [ABSTRACT FROM PUBLISHER]

Ho do parents resolve their conflict over parental care? The classical “sealed-bid” model of biparental care suggested that parents use a fixed best effort given the partners effort. Alternatively, parents may “negotiate” their actual effort until the efforts of both partners settle down to limiting values, but in this case, the resulting efforts will not be the best responses to one another. Consequently, under the best response scenario, the response of 1 parent to the removal of its mate can be predicted from the response to a reduction in its partners effort, whereas the “negotiation” model predicts that such an extrapolation will underestimate the effort of a parent caring alone. We tested this prediction in free-living house sparrows (Passer domesticus). We experimentally manipulated the males’ parental care as follows: males’ care in group 1) was reduced by using a capture–handling–release stress protocol, 2) stopped by removing the male, and 3) left as control. In response to these manipulations, control females kept their feeding rate constant, whereas male-stressed-released females showed a moderate increase of feeding rate. When this response was extrapolated to zero male effort, their effort was still significantly lower than the observed effort of male-removed females. These results suggest that females may use the negotiation rule to determine their actual parental effort. [ABSTRACT FROM AUTHOR]

We examined the effect of patch size and competitor number on aggression among house sparrows, Passer domesticus, foraging at patches of seven different sizes in a doubling series (0.014, 0.029, 0.058, 0.116, 0.230, 0.462, and 0.922 m2). Contrary to our expectations, the birds did not defend an entire patch, even when it was small as 0.014 m2. The frequency of aggression among the birds decreased gradually with increasing patch size, in contrast to the step decline predicted by resource defense theory. Moreover, the birds fought more frequently and more intensely as competitor density increased. Both results are consistent with the predictions of a modified hawk-dove model for shared patches. Females were more aggressive and fed at a higher rate than did males. The proportion of females increased as patch size decreased, and aggression became more frequent and intense. Even when patches are shared, patch size has an important effect on the frequency and intensity of foraging competition and the size and composition of foraging groups. [ABSTRACT FROM AUTHOR]

Several studies have found that island populations of passerines exhibit lower levels of extrapair paternity (EPP) than mainland populations. An explanation proposing that lower levels of genetic diversity in isolated populations reduce the indirect genetic benefits of EPP to females has been supported by observational study but not tested experimentally. Here, we present the results of a manipulative study on an island population of house sparrows (Passer domesticus), which previously exhibited a significantly lower frequency of EPP than mainland populations. Fifty adults from a mainland population with significantly more genetic diversity than the island population (across 17 microsatellite loci) were introduced into the island population, and the incidence of EPP was subsequently monitored over 3 breeding seasons. In the year of the introduction, the incidence of EPP rose to approximately the level seen in mainland populations of house sparrows but dropped to an intermediate frequency in the following 2 years. Unexpectedly, parentage assignment showed that in the year of the introduction, all females producing extrapair offspring were native island birds, as were all the extrapair and cuckolded males. These results suggest that EPP in this experimental population was not driven by females trying to maximize the genetic diversity of their offspring. [ABSTRACT FROM AUTHOR]