The recognition of behavior as a link between process and pattern in landscape ecology is exemplified by the concept of functional connectivity: the degree to which the landscape facilitates or impedes movement among resource patches. In this paper, I first argue that the actual operational definitions of this concept as applied to animal movement are not fully consistent with its formal definition. For instance, I question that a high likelihood of movement among the different points of primary habitat implies a high connectivity and contend that such a view can lead to misinterpretations. I also address two more hurdles to the measurement of functional connectivity: the fact that functional connectivity may not be equal along all axes and directions of movement and individual variation in functional connectivity within a given landscape. These points bring me to suggest that the concept of functional connectivity be bridged to the one of travel costs used in behavioral ecology. This would help define unequivocal operational definitions of functional connectivity as its measurement would then be dictated by its ecological role within specific models (e.g., travel costs within group membership models of foraging theory). I argue further that this ecological role shall in turn determine the motivation underlying the movement of individuals, implying that the latter should preferably be standardized when measuring functional connectivity in the field. I finally present some methods to do so. These include translocation and playback experiments, food‐titration and giving‐up densities experiments, and manipulating feeding and breeding site locations and success.

The intensification of agricultural practices has been identified as the main cause of population decline in farmland birds since the 1960s in both Europe and North America. Although the links between species richness or abundance and various components of agricultural intensification are well established, the mechanisms underlying these trends have rarely been addressed along a gradient of intensification or have been quantified at only one spatial scale. Here we quantified the influence of landscape structure on the nest box occupancy and breeding success of Tree Swallows (Tachycineta bicolor) at seven spatial scales (1, 2, 3, 4, 5, 10, and 20 km radii) over a 10 200-km2 gradient of agricultural intensification in southern Québec, Canada. A network of 400 nest boxes distributed among 40 farms was visited every two days over three breeding seasons, 2004-2006. Nest box occupancy decreased with the proportion of intensive cultures (maize, cereals, and soybeans) in the landscape, especially when manure heaps and tanks were abundant, and was also determined by local variables (i.e., nest box clearance, interspecific competition) and by previous-year fledging success. Clutch size decreased as the breeding season progressed and with the proportion of intensive cultures in the landscape, with no consistent variation across spatial scales. Hatching success was not related to any landscape variables but increased with clutch size. Both the number of fledglings and fledging probability increased with the proportion of extensive cultures (hayfields, pastures, and fallows). These effects increased with spatial scale and reached a plateau at the 5 km radius: the maximum distance from the nest reached by foraging Tree Swallows. Our results can likely be attributed to lower food availability in intensive cultures compared to extensive ones. This study suggests that several components of breeding that impact on population structure and dynamics of insectivorous birds will be negatively affected by agricultural intensification.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Animal Ecology. Summary 1. Individuals in many social species are attracted to feeding conspecifics. The profitability of conspecific attraction is negatively frequency-dependent and can be modelled as a producer-scrounger (PS) game for which the ESS solution predicts some mixture of producer (no attraction) and scrounger (attraction) tactics in the population. Current models for the spatial distribution of rate-maximizing foragers, which learn the quality of habitats as they exploit patches, ignore the possible effect of conspecific attraction on the stable distribution of foragers. 2. We used simulations of a population with ESS levels of attraction to investigate the effect of conspecific attraction on the spatial distribution of learning foragers which incur travel costs. In habitats where patches depleted slowly, ESS levels of attraction helped foragers which experienced no interference reach the expected ideal free distribution (IFD) by facilitating aggregation to the richest patches. Large aggregations also occurred with interference and thus reduced the fit to the IFD, which in this case predicts a scatter of foragers across patches of varying quality. In habitats where patches depleted rapidly, ESS levels of attraction preventedforagers from reaching the IFD, irrespective of interference levels. Foragers failed to learn habitat quality and thus often aggregated in poor patches, especially in large populations which depleted patches faster and had fewer opportunities to learn quality. 4. Predictions of the model in habitats where patches deplete slowly are supported by several studies. More work is needed for habitats where patches deplete more rapidly. We conclude that conspecific attraction can have important, and often disruptive effects on spatial distributions.When there is no interference between foragers, so that the rate of food intake of an individual is not influenced by the activity of conspecifics, foragers are expected to aggregate in the richest patches. However, as the level of interference increases, some foragers are also expected to occupy patches of lesser quality. If foragers have equal competitive ability, are free to move to all patches, and have perfect knowledge of food availability in the habitat, then at equilibrium the proportion of foragers in a patch should be equal to the proportion of resources in that patch, compensated for the level of interference. At equilibrium, foragers in all patches experience the same intake rate and cannot improve their payoffs by moving to a different patch. The spatial distribution of foragers at

Habitat loss and fragmentation affect forest birds through direct loss of breeding habitats, detrimental edge effects such as increased nest predation and brood parasitism, and possibly by limiting movements among remaining forest patches. Despite indirect evidence suggesting that landscape-scale bird movements are constrained by open areas, skepticism remains because birds routinely cross inhospitable terrain during migration. Here, we report evidence from 201 independent homing trials showing that landscape composition and configuration influence the movements (1-4 km) of two neotropical migrant (Black-throated Blue Warbler, Dendroica caerulescens and the Ovenbird, Seiurus aurocapillus) and one resident (Black-capped Chickadee, Poecile atricapillus) forest bird species in Quebec, Canada. Trials consisted of translocating territorial, mated males and measuring the time they needed to return to their territories (homing time), as well as the probability with which they returned to their territories within 30 h (homing success). Birds took more time and were less likely to return to their territories as forest cover decreased in the landscape. Once the simple linear variation due to forest cover was removed from landscape configuration variables, their influence on homing time and success was nonexistent or subtle, suggesting that landscape composition has greater predictive value than landscape configuration to infer constraints on forest bird movements. Indeed, and contrary to our expectation, mean nearest-neighbor distance between forest patches had no impact on homing time or success, but its coefficient of variation was positively correlated with homing time and negatively correlated with homing success. On the other hand, homing time and success were not influenced by the number of forest patches or the amount of edge per unit of forest cover. These results were consistent for all three bird species that we studied. Our data support the hypothesis that movements are constrained when forest birds travel in deforested and fragmented landscapes outside migratory periods. Such an impediment is likely to disrupt habitat selection processes, reduce the colonization of isolated forest patches, and ultimately, alter population structure and dynamics.

Habitat loss and fragmentation affect forest birds through direct loss of breeding habitats, detrimental edge effects such as increased nest predation and brood parasitism, and possibly by limiting movements among remaining forest patches. Despite indirect evidence suggesting that landscape‐scale bird movements are constrained by open areas, skepticism remains because birds routinely cross inhospitable terrain during migration. Here, we report evidence from 201 independent homing trials showing that landscape composition and configuration influence the movements (1–4 km) of two neotropical migrant (Black‐throated Blue Warbler, Dendroica caerulescens and the Ovenbird, Seiurus aurocapillus) and one resident (Black‐capped Chickadee, Poecile atricapillus) forest bird species in Quebec, Canada. Trials consisted of translocating territorial, mated males and measuring the time they needed to return to their territories (homing time), as well as the probability with which they returned to their territories within 30 h (homing success). Birds took more time and were less likely to return to their territories as forest cover decreased in the landscape. Once the simple linear variation due to forest cover was removed from landscape configuration variables, their influence on homing time and success was nonexistent or subtle, suggesting that landscape composition has greater predictive value than landscape configuration to infer constraints on forest bird movements. Indeed, and contrary to our expectation, mean nearest‐neighbor distance between forest patches had no impact on homing time or success, but its coefficient of variation was positively correlated with homing time and negatively correlated with homing success. On the other hand, homing time and success were not influenced by the number of forest patches or the amount of edge per unit of forest cover. These results were consistent for all three bird species that we studied. Our data support the hypothesis that movements are constrained when forest birds travel in deforested and fragmented landscapes outside migratory periods. Such an impediment is likely to disrupt habitat selection processes, reduce the colonization of isolated forest patches, and ultimately, alter population structure and dynamics.

Migratory bird species that feed on air-borne insects are experiencing widespread regional declines, but these remain poorly understood. Agricultural intensification in the breeding range is often regarded as one of the main drivers of these declines. Here, we tested the hypothesis that body mass in breeding individuals should reflect habitat quality in an aerial insectivore, the tree swallow (Tachycineta bicolor), along a gradient of agricultural intensity. Our dataset was collected over 7 years (2005)(2006)(2007)(2008)(2009)(2010)(2011) and included 2918 swallow captures and 1483 broods. Analyses revealed a substantial decline of the population over the course of the study (219% occupancy rate), mirrored by decreasing body mass. This trend was especially severe in females, representing a total loss of 8% of their mass. Reproductive success was negatively influenced by intensive agriculture, but did not decrease over time. Interestingly, variation in body mass was independent of breeding habitat quality, leading us to suggest that this decline in body mass may result from carry-over effects from non-breeding areas and affect population dynamics through reduced survival. This work contributes to the growing body of evidence suggesting that declines in migratory aerial insectivores are driven by multiple, complex factors requiring better knowledge of year-round habitat use.

Dispersal affects processes as diverse as habitat selection, population growth, and gene flow. Inference about dispersal and its variation is thus crucial for assessing population and evolutionary dynamics. Two approaches are generally used to estimate dispersal in free-ranging animals. First, multisite capture-recapture models estimate movement rates among sites while accounting for survival and detection probabilities. This approach, however, is limited in the number of sites that can be considered. Second, diffusion models estimate movements within discrete habitat using a diffusion coefficient, resulting in a continuous processing of space. However, this approach has been rarely used because of its mathematical and implementation complexity. Here, we develop a multi-event capture-recapture approach that circumvents the issue of too many sites while being relatively simple to be implemented in existing software. Moreover, this new approach allows the quantifying of memory effects, whereby the decision of dispersing or not on a given year impacts the survival or dispersal likelihood of the following year. We illustrate our approach using a long-term data set on the breeding ecology of a declining passerine in southern Quebec, Canada, the Tree Swallow (Tachycineta bicolor).

Latitudinal differences in timing of breeding are well documented but how such differences carry over to influence timing of events in the annual cycle of migratory birds is not well understood. We examined geographical variation in timing of events throughout the year using light-level geolocator tracking data from 133 migratory tree swallows ( Tachycineta bicolor ) originating from 12 North American breeding populations. A swallow's breeding latitude influenced timing of breeding, which then carried over to affect breeding ground departure. This resulted in subsequent effects on the arrival and departure schedules at autumn stopover locations and timing of arrival at non-breeding locations. This ‘domino effect’ between timing events was no longer apparent by the time individuals departed for spring migration. Our range-wide analysis demonstrates the lasting impact breeding latitude can have on migration schedules but also highlights how such timing relationships can reset when individuals reside at non-breeding sites for extended periods of time.