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Anders Pape Møller - One of the best experts on this subject based on the ideXlab platform.
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Tropical birds take small risks
Behavioral Ecology, 2012Co-Authors: Anders Pape Møller, Wei LiangAbstract:The life history of tropical birds differs from that of their temperate counterparts by late start of reproduction, small clutch sizes, and high rates of adult survival. Thus, tropical species should have greater residual reproductive value than temperate species. Therefore, tropical birds can be predicted to take smaller risks than closely related temperate birds in order not to jeopardize their prospects of survival, which is the single most important component of fitness, and which is greater in tropical than in temperate species. We estimated Flight Distances as a measure of risk-taking behavior of common species of birds for populations living in tropical areas in China (mainly Hainan) and in temperate Europe (mainly Denmark and France), predicting that Flight Distances should be longer in tropical than in temperate populations, and that the difference in Flight Distance between these 2 environments should be positively correlated with the difference in clutch size. Mean Flight Distance was more than twice as large in tropical compared with temperate populations for 25 pairs of taxa. The difference in Flight Distance between tropical and temperate taxa decreased with the difference in clutch size between the 2 environments. These findings are consistent with the hypothesis that tropical birds take smaller risks than closely related temperate taxa to minimize the risk of early death due to predation.
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Urban areas as refuges from predators and Flight Distance of prey
Behavioral Ecology, 2012Co-Authors: Anders Pape MøllerAbstract:Large animals have longer Flight Distances when approached by a potential predator than small animals, and predators therefore have longer Flight Distances than their prey. The ubiquitous presence of humans in urban areas selects for differential invasion by animals with short Flight Distances, and adaptation to urban environments results in further reductions in Flight Distance. Because prey are better able to cope with the proximity of humans than predators due to differences in Flight Distance, urban areas may act as refuges. Predators on average have a Flight Distance that is 8 times larger than that of their prey. In urban areas, humans were present within a Distance of 54 m (the mean Flight Distance of raptor species) 16% of the time and 4% of the time within a Distance of 7 m (the mean Flight Distance of prey species). In contrast, humans were present 1.2% of the time within a Distance of 54 m but only 0.1% of the time within a Distance of 7 m in rural habitats. Therefore, prey gained a 10-fold increase in predator refuge in urban compared with rural habitats. The reduction in Flight Distance between the ancestral rural and the current urban habitats decreased with the difference in Flight Distance between raptors and that of prey. The difference in Flight Distance between predators and that of prey increased with increasing preference of prey by sparrowhawks Accipiter nisus relative to their abundance, providing evidence of a selective advantage for prey. These results suggest that birds that are prey of raptors enjoy a selective advantage from association with humans.
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Flight Distance and Eye Size in Birds
Ethology, 2010Co-Authors: Anders Pape Møller, Johannes ErritzøeAbstract:Larger eyes capture more information from the environment than small eyes, but also require more brain space for information processing. Therefore, individuals have to optimize the size of their eyes, leading to the prediction that larger eyes should have evolved in species with greater benefits from large eyes, such as species subject to intense predation risk. In a comparative analysis of 97 bird species, we found that species that fled at longer Distances from an approaching potential predator indeed had relatively large eyes for their body size. In contrast, there was no indication that large eyes had evolved in species living in secluded habitats, or in species eating mobile prey. These findings are consistent with the assumption that eye size is labile and can evolve in response to changing predator environments. They also suggest that eye size may act as a constraint on optimal anti-predator behavior, if the predator community changes as a consequence of introductions or invasions.
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Flight Distance and population trends in European breeding birds
Behavioral Ecology, 2008Co-Authors: Anders Pape MøllerAbstract:Flight Distance reflects the risk that individual animals are willing to take when approached by a potential predator, as shown by a negative relationship between susceptibility to predation and Flight Distance. Species with long Flight Distances should more often suffer from disruption of their activities by potential predators, including humans, than species with short Distances, resulting in declining reproductive success and hence declining population size of such species if disturbance happens more often. Long Flight Distances thus suggest that individuals need large amounts of space for their body size, resulting in the prediction that species with long Flight Distances should have a higher frequency of declining populations than species with short Flight Distances, when human impact on natural habitats increases. Bird species with long Flight Distances had declining population trends across Europe in a comparative study of 56 species, even when controlling statistically for other factors associated with population declines, with effect sizes ranging from 0.36 to 0.58 (Pearson's r). These findings suggest that standardized measures of Flight Distance provide reliable information about the population consequences of risk-taking behavior by individuals and the susceptibility of different species to increased levels of disturbance. Copyright 2008, Oxford University Press.
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Flight Distance of urban birds predation and selection for urban life
Behavioral Ecology and Sociobiology, 2008Co-Authors: Anders Pape MøllerAbstract:Numerous species have adapted to humans, especially invasive species associated with humans in towns and cities. Short Flight Distances of populations adapted to urban environments reflect changes in behavior and physiology, reflecting phenotypic plasticity or evolution. Here, I tested the hypothesis that the decrease in Flight Distance to a potential predator (an approaching human) reflected adaptation to urbanization, using a data set of Flight Distances of 44 common species of European birds in different stages of adaptation to urban environments. Urban populations had consistently shorter Flight Distances than rural populations of the same species. Variation in relative Flight Distance of urban populations was predicted by the number of generations since urbanization, as expected by a gradual process of adaptation. Furthermore, species with relatively large populations in urban environments would be an indication of local adaptation to urban environments. Relative Flight Distance of urban population was shorter for species with large populations in urban compared to rural habitats. Species that had adapted to urban environments as shown by short Flight Distances were less susceptible to predation by the European sparrowhawk Accipiter nisus than species with relatively long Flight Distances in urban populations. These findings provide evidence consistent with the hypothesis that recent changes in the tameness of urban birds, as reflected by their relatively short Flight Distances, is an adaptation to the novel urban environment.
Jason H. Peterson - One of the best experts on this subject based on the ideXlab platform.
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Variable Flight Distance to resources results in changing sex allocation decisions, Megachile rotundata
Behavioral Ecology and Sociobiology, 2016Co-Authors: Jason H. Peterson, Bernard D. RoitbergAbstract:Resource availability and location are expected to vary, based on use by individuals and changing ecological conditions; the response of animals to those changes is critical to their fitness. To investigate the effects of changing conditions on fitness, we conducted field experiments using the central-place-foraging alfalfa leafcutting bee ( Megachile rotundata ), examining the changes in sex allocation when presented with changes in Flight Distance required to obtain resources. The results suggest that changes in Flight Distance to resources during the year’s Flight season altered subsequent allocation decisions: mothers experiencing long Flight Distance to resources early in the season and short Flight Distance later in the season generated a greater proportion of female offspring than mothers experiencing the opposite. During the second half of the season, however, it was current experimental conditions significantly impacting decisions with those mothers residing near the resources producing a greater portion of female offspring than those far from resources, regardless of Flight Distances experienced earlier in the year. These results show that sex allocation decisions may change dynamically during a female’s lifetime in response to ecological changes. We also looked at these results through the contradicting hypotheses marginal value theorem and sex ratio theory, finding that the latter may be in play depending on an individual’s past and/or present condition.
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Impacts of Flight Distance on sex ratio and resource allocation to offspring in the leafcutter bee, Megachile rotundata
Behavioral Ecology and Sociobiology, 2006Co-Authors: Bernard D. Roitberg, Jason H. PetersonAbstract:Fisher's theoretical prediction of equal investment in each sex for a panmictic population ( The genetical theory of natural selection . Clarendon, Oxford, 1930) can be altered by a number of factors. For example, the sex ratio theory predicts variation in equal investment in each sex when the maternal fitness gains from increased investment differ between sexes. Changing sex allocation because of changing payoffs may result from different ecological situations, such as foraging conditions. We investigated the impact of foraging travel cost on relative investment in sons vs daughters. Field studies were carried out with the central-place-foraging leafcutter bee Megachile rotundata (Fabricius), which has smaller males than females. Therefore, less investment is required to produce a viable son compared with a daughter. We found that with increased Flight Distance to resources, females produced a greater proportion of sons. Females also invested fewer resources in individual sons and daughters and produced fewer offspring with increased Flight Distance.
Michael Hrncir - One of the best experts on this subject based on the ideXlab platform.
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Increasing thermal stress with Flight Distance in stingless bees (Melipona subnitida) in the Brazilian tropical dry forest: Implications for constraint on foraging range.
Journal of insect physiology, 2020Co-Authors: João Batista Freire Souza-junior, Vinício Heidy Da Silva Teixeira-souza, Aline Oliveira-souza, Paloma Fernandes De Oliveira, João Paulo Araújo Fernandes De Queiroz, Michael HrncirAbstract:The thoracic temperature (TTX) of foraging bees usually exceeds ambient air temperatures (TAIR) by several degrees. In hot tropical climate zones, therefore, individuals may reach body temperatures close to their critical thermal maxima, which might constrain their activity. In the present study, we tested the hypothesis that thermal stress increases with Flight Distance in nectar foragers of M. subnitida, a stingless bee species native to the hottest regions of the Brazilian tropical dry forest. Using infrared thermography, we recorded the body surface temperature of individuals foraging at Distances of 15, 50, and 100 m. Closest to the nests, foragers stabilized TTX at 40 °C when collecting sugar solution at TAIR > 30 °C. The simultaneous decrease of the temperature excess ratio of head and abdomen suggests evaporative cooling at these body parts. With increasing foraging Distance, foragers increased heat dissipation to the head and abdomen. Thus, despite more intensive heating of the thorax due to faster and longer Flights, the bees maintained similar TTX as foragers at close feeding sites. However, at TAIR > 30 °C, bees could no longer compensate the elevated heat gain at the head (50 m) and abdomen (50, 100 m), which caused an increasing temperature excess in these body parts. Thus, foragers of M. subnitida suffer overheating of the head and abdomen instead of the thorax when foraging in high temperatures at far feeding sites. Consequently, to avoid heat stress in the Brazilian tropical dry forest, the bees should forage close to the nest.
Louis Lefebvre - One of the best experts on this subject based on the ideXlab platform.
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Innovativeness and the effects of urbanization on risk-taking behaviors in wild Barbados birds
Animal cognition, 2016Co-Authors: Simon Ducatez, Jean-nicolas Audet, Jordi Ros Rodriguez, Lima Kayello, Louis LefebvreAbstract:The effects of urbanization on avian cognition remain poorly understood. Risk-taking behaviors like boldness, neophobia and Flight Distance are thought to affect opportunism and innovativeness, and should also vary with urbanization. Here, we investigate variation in risk-taking behaviors in the field in an avian assemblage of nine species that forage together in Barbados and for which innovation rate is known from previous work. We predicted that birds from highly urbanized areas would show more risk-taking behavior than conspecifics from less urbanized parts of the island and that the differences would be strongest in the most innovative of the species. Overall, we found that urban birds are bolder, less neophobic and have shorter Flight Distances than their less urbanized conspecifics. Additionally, we detected between-species differences in the effect of urbanization on Flight Distance, more innovative species showing smaller differences in Flight Distance between areas. Our results suggest that, within successful urban colonizers, species differences in innovativeness may affect the way species change their risk-taking behaviors in response to the urban environment.
Bernard D. Roitberg - One of the best experts on this subject based on the ideXlab platform.
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Variable Flight Distance to resources results in changing sex allocation decisions, Megachile rotundata
Behavioral Ecology and Sociobiology, 2016Co-Authors: Jason H. Peterson, Bernard D. RoitbergAbstract:Resource availability and location are expected to vary, based on use by individuals and changing ecological conditions; the response of animals to those changes is critical to their fitness. To investigate the effects of changing conditions on fitness, we conducted field experiments using the central-place-foraging alfalfa leafcutting bee ( Megachile rotundata ), examining the changes in sex allocation when presented with changes in Flight Distance required to obtain resources. The results suggest that changes in Flight Distance to resources during the year’s Flight season altered subsequent allocation decisions: mothers experiencing long Flight Distance to resources early in the season and short Flight Distance later in the season generated a greater proportion of female offspring than mothers experiencing the opposite. During the second half of the season, however, it was current experimental conditions significantly impacting decisions with those mothers residing near the resources producing a greater portion of female offspring than those far from resources, regardless of Flight Distances experienced earlier in the year. These results show that sex allocation decisions may change dynamically during a female’s lifetime in response to ecological changes. We also looked at these results through the contradicting hypotheses marginal value theorem and sex ratio theory, finding that the latter may be in play depending on an individual’s past and/or present condition.
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Impacts of Flight Distance on sex ratio and resource allocation to offspring in the leafcutter bee, Megachile rotundata
Behavioral Ecology and Sociobiology, 2006Co-Authors: Bernard D. Roitberg, Jason H. PetersonAbstract:Fisher's theoretical prediction of equal investment in each sex for a panmictic population ( The genetical theory of natural selection . Clarendon, Oxford, 1930) can be altered by a number of factors. For example, the sex ratio theory predicts variation in equal investment in each sex when the maternal fitness gains from increased investment differ between sexes. Changing sex allocation because of changing payoffs may result from different ecological situations, such as foraging conditions. We investigated the impact of foraging travel cost on relative investment in sons vs daughters. Field studies were carried out with the central-place-foraging leafcutter bee Megachile rotundata (Fabricius), which has smaller males than females. Therefore, less investment is required to produce a viable son compared with a daughter. We found that with increased Flight Distance to resources, females produced a greater proportion of sons. Females also invested fewer resources in individual sons and daughters and produced fewer offspring with increased Flight Distance.