Prey reduce risk-taking and abundance in the proximity of predators

Abstract

Prey have evolved anti-predator defences that reduce or eliminate the risk of predation. Predators often reproduce at specific sites over many years causing permanent threats to local prey species. Such prey may respond by moving elsewhere thereby reducing local population abundance, or they may stay put and adjust their behavior to the presence of predators. We tested these predictions by analyzing population abundance and anti-predator behavior within 100 m of and 500 m away from nests of sparrowhawks Accipiter nisus and goshawks A. gentilis for 80 species of birds. Population abundance of prey was reduced by 11% near goshawk nests and by 15% near sparrowhawk nests when compared with nearby control sites in similar habitats. Flight initiation distance (FID) of prey, estimated as the distance at which birds took flight when approached by a human, increased by 50% in the presence of hawk nests, providing evidence of adjustment of anti-predator behavior to prevailing risks of predation. Susceptibility to predation was estimated as log transformed abundance of the observed number of prey items obtained from prey remains collected around nests minus log transformed expected number of prey according to point counts of breeding birds. FID increased from 10 to 46 m with increasing susceptibility of prey species to predation by the goshawk and from 12 to 15 m with increasing susceptibility of prey species to predation by the sparrowhawk. These findings suggest that prey adjust their distribution and anti-predator behavior to the risk of predation.

Risk-taking behavior of bull-headed shrikes that recently colonized islands

“…Risk-taking behavior is related to predator avoidance ( Quinn and Cresswell 2005 ; Réale et al 2007 ; Herborn et al 2010 ). Risk-taking individuals are prone to suffer predation ( Møller et al 2008 ; Møller 2014 ), and risk-taking behavior changes in response to factors associated with predation risk, such as the existence of predators ( Møller et al 2017 ; Lapiedra et al 2018 ) and the availability of hiding places ( Martín and López 2000 ; Walther and Gosler 2001 ). Individuals which have invaded urbanized environments are reported to engage in riskier behaviors.…”

Escape from predators and genetic variance in birds

“…Bize et al ., ; Carrete et al ., ), here we have demonstrated based on observations of 52, 105 and 111 bird species, respectively, that genetic variation shown by both minisatellite and microsatellite markers is correlated with FID. This is consistent with the assumption that long FIDs have survival value when facing a potential predator (Møller et al ., , ; Møller, ). Species with short FIDs faces more difficulties than species with long FID to reach large effective population size and a high level of genetic variance.…”

The Behavioural Ecology, Local Population Dynamics and Conservation of the Bearded Reedling <i>Panurus Biarmicus</i> in “El Hondo Natural Park” (SE Spain)

“…Also, some populations may have a higher tendency to disperse than others [99] or different populations may vary in composition and behaviour, perhaps reflected in age-specific or sex-specific avoidance behaviour [7,8]. At difference of other cohabiting reedbed passerines in El Hondo of similar moult patterns and wing shapes like Moustached warbler (Acrocephalus melanopogon) with longer movements [94] the Bearded Reedling's possess shorter movements [100] related to different age-related wing shapes [101] and long-tail, that in spite to be an ornament implied in sexual and natural selected processes [102], has an important role for habitat choice as balancing organ among reed-stems [25].…”

“…Transients are more mobile than residents which make only short-range [3,6]. Residents are consistently heavier than transients in absence of predators [7] and preys reduce its abundance in the proximity of predators [8].…”