scholarly journals Microhabitat choice in island lizards enhances camouflage against avian predators

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Kate L. A. Marshall ◽  
Kate E. Philpot ◽  
Martin Stevens
Keyword(s):  
Avian Predators ◽  
Microhabitat Choice

scholarly journals Interference competition pressure predicts the number of avian predators that shifted their timing of activity

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180744 ◽  
Author(s):  
Yifan Pei ◽  
Mihai Valcu ◽  
Bart Kempenaers
Keyword(s):  
Species Richness ◽  
Body Size ◽  
Interference Competition ◽  
Relative Importance ◽  
Exploitation Competition ◽  
Predator Species ◽  
Avian Predator ◽  
Avian Predators ◽  
Time Partitioning ◽  
Competition Pressure

Being active at different times facilitates the coexistence of functionally similar species. Hence, time partitioning might be induced by competition. However, the relative importance of direct interference and indirect exploitation competition on time partitioning remains unclear. The aim of this study was to investigate the relative importance of these two forms of competition on the occurrence of time-shifting among avian predator species. As a measure of interference competition pressure, we used the species richness of day-active avian predator species or of night-active avian predator species (i.e. species of Accipitriformes, Falconiformes and Strigiformes) in a particular geographical area (assemblage). As an estimate of exploitation competition pressure, we used the total species richness of avian predators in each assemblage. Estimates of the intensity of interference competition robustly predicted the number of Accipitriformes species that became crepuscular and the number of Strigiformes species that became day-active or strictly crepuscular. Interference competition pressure may depend on body size and on the total duration of the typical active period (day or night length). Our results support—to some extent—that smaller species are more likely to become time-shifters. Day length did not have an effect on the number of time-shifter species in the Accipitriformes. Among the large Strigiformes, more time-shifter species occur in areas where nights are shorter (i.e. where less of the typical time resource is available). However, in the small Strigiformes, we found the opposite, counterintuitive effect: more time-shifters where nights are longer. Exploitation competition may have had an additional positive effect on the number of time-shifters, but only in Accipitriformes, and the effect was not as robust. Our results thus support the interference competition hypothesis, suggesting that animals may have shifted their time of activity, despite phylogenetic constraints on the ability to do so, to reduce the costs of direct interactions. Our findings also highlight the influence of body size as a surrogate of competitive ability during encounters on time partitioning, at least among avian predators.

False Head Wing Pattern of the Burmese Junglequeen Butterfly and the Deception of Avian Predators

Biotropica ◽  
1993 ◽  
Vol 25 (4) ◽  
pp. 474 ◽  
Author(s):  
Martin Tonner ◽  
Vojtech Novotny ◽  
Jan Leps ◽  
Stanislav Komarek
Keyword(s):  
Wing Pattern ◽  
Avian Predators

Defence strategies of Chrysomela lapponica (Coleoptera: Chrysomelidae) larvae: relative efficacy of secreted and stored defences against insect and avian predators

2018 ◽  
Vol 124 (3) ◽  
pp. 533-546 ◽  
Author(s):  
Elena L Zvereva ◽  
Lucia Doktorovová ◽  
Kateřina Hotová Svádová ◽  
Vitali Zverev ◽  
Pavel Štys ◽  
...  
Keyword(s):  
Relative Efficacy ◽  
Chrysomela Lapponica ◽  
Avian Predators ◽  
Defence Strategies

Comments on Guimarães & Sawaya. Pretending to be venomous: is a snake's head shape a trustworthy signal to a predator?

2011 ◽  
Vol 28 (1) ◽  
pp. 123-124 ◽  
Author(s):  
Janne K. Valkonen ◽  
Johanna Mappes
Keyword(s):  
Prey Species ◽  
Adaptive Significance ◽  
Predation Pressure ◽  
Olfactory Cues ◽  
Head Shape ◽  
Venomous Snake ◽  
Avian Predators ◽  
Empirical Experiment ◽  
Plasticine Models

Several species of non-venomous snake are known to flatten their heads when disturbed, and this behaviour has been suggested to be a mimicry of vipers (Arnold & Ovenden 2002, Hailey & Davies 1986, Young et al. 1999). Using plasticine models, Guimarães & Sawaya (2011) tested the antipredatory function of a triangular head shape in snakes. Their article presents the first published empirical experiment testing the adaptive significance of vipers' triangular head shape. Guimarães & Sawaya (2011) found no support for the viper mimicry hypothesis. Accordingly, they concluded that ‘the shape of [the] head seemed not to confer advantage itself’. Although the use of plasticine models is a generally accepted method of testing predation pressure on snakes, we argue that the experiment may have failed to find the antipredatory function of triangulation due to the pooling of attacks by mammalian and avian predators. Mammals generally rely on olfactory cues during foraging. Plasticine has a strong odour which does not resemble the odour of any prey species. It is thus unlikely that mammals would treat snake replicas as true snakes.

Do Breeding Nomadic Avian Predators Dampen Population Fluctuations of Small Mammals?

Oikos ◽  
1991 ◽  
Vol 62 (2) ◽  
pp. 195 ◽  
Author(s):  
Erkki Korpimäki ◽  
Kai Norrdahl ◽  
Erkki Korpimaki
Keyword(s):  
Small Mammals ◽  
Population Fluctuations ◽  
Avian Predators
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