Habitat but not group size or recent predator activity affect corvid collective vigilance at carcasses

Bragato, Patrick J.; Spencer, Emma E.; Dickman, Chris R.; Crowther, Mathew S.; Tulloch, Ayesha I. T.; Newsome, Thomas M.

doi:10.1111/aec.13323

Cited by 3 publications

(1 citation statement)

References 87 publications

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“…On the other hand, a link between vigilance and habitat has been shown—i.e. animals more vigilant in open habitats—albeit for corvids (Bragato et al., 2023).…”

Section: Discussionmentioning

confidence: 99%

Seasonal changes in herd size and time budget of springbok (Antidorcas marsupialis) in southern Namibia

Cunningham,

Cunningham

2023

Afr J Ecol

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Springbok (Antidorcas marsupialis) is an understudied species with a dearth of scientific work having been conducted, especially so for the Nama‐Karoo vegetation type, in southern Namibia. We studied variations in herd composition and time budget of springbok by direct observations during a dry and wet season in southern Namibia and found significant differences (p < 0.001) in mean herd size between the dry and wet seasons. Herd size decreased from early morning to late afternoon during the dry season (p = 0.037) but not the wet season (p = 0.362). Springbok spent more time browsing during the dry season compared to the wet season (p < 0.001) when they spent more time grazing (p < 0.001). However, there was no significant difference in the time springbok spent walking between the two seasons (p = 0.181). Other energy‐intensive activities such as grooming and running increased during the wet season (p < 0.001) due to favourable environmental conditions, breeding season and possibly an increase in parasite load.

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“…On the other hand, a link between vigilance and habitat has been shown—i.e. animals more vigilant in open habitats—albeit for corvids (Bragato et al., 2023).…”

Section: Discussionmentioning

confidence: 99%

Seasonal changes in herd size and time budget of springbok (Antidorcas marsupialis) in southern Namibia

Cunningham,

Cunningham

2023

Afr J Ecol

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Vertebrate scavenging in Australia is shaped by a complex interplay of bioregional, seasonal and habitat factors

Spencer,

Dickman,

Greenville

et al. 2024

Journal of Zoology

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Carcass scavenging by vertebrates is a critical ecosystem service that is influenced by environmental factors such as season and habitat. However, there is limited understanding of the role that these factors play in shaping scavenging patterns across different bioregions. We used camera traps to monitor vertebrate scavengers at 120 kangaroo (Family: Macropodidae) carcasses that were positioned across different seasons (warm/cool) and habitats (open/closed canopy) in three disparate desert, subalpine and temperate bioregions in Australia. Our survey identified 27 species that scavenged carcasses and revealed clear differences in scavenging patterns across the three bioregions. Carcass use was highest for feral cats, birds of prey, corvids and red foxes in the desert bioregion; for reptiles and dingoes in the temperate bioregion and for feral pigs, possums and dingoes in the subalpine bioregion. Bioregional differences in scavenger guild composition explained >4.6 times more variation in scavenger guild dissimilarity than season and >9.8 times more variation than habitat. Further, habitat had few effects on scavenger communities or carcass detection and use, whereas season was a strong predictor of these responses. Across bioregions, there were some general seasonal and habitat scavenging trends, with mammals and birds often using carcasses more frequently in cooler seasons and birds detecting carcasses faster in open habitat. However, there was also extensive within‐bioregion seasonal variation. For example, depending on bioregion, some animals scavenged more frequently or detected carcasses faster in warmer seasons (i.e. birds and reptiles). Our results show that vertebrate scavenging is mediated by a complex interplay of environmental variables, especially seasonality, which may operate differently across bioregions. These findings have implications for understanding variability in vertebrate scavenging patterns and, in turn, functionally redundant or complementary scavenging processes.

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Watch out! High vigilance at small waterholes when alone in open trees

Hofmann,

Mettke-Hofmann

2024

PLoS ONE

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An animal’s environment contains many risks causing animals to scan their environment for potential predators and threats from conspecifics. How much time they invest in such vigilance depends on environmental and social factors. Most vigilance studies have been conducted in a foraging context with little known about vigilance in other contexts. Here we investigated vigilance of Gouldian finches at waterholes considering environmental and social factors. Gouldian finches are colour polymorphic with two main head colours in both sexes co-occurring in the same population, black-headed and red-headed. Data collection was done on birds sitting in trees surrounding waterholes by measuring the frequency of head movements, which reflects how frequently they change their field of view, i.e., scan different areas in their environment. A higher frequency generally reflects higher vigilance. Gouldian finches had a higher frequency of head movements when at small waterholes and when sitting in open, leafless trees. Moreover, head movements were higher when birds were alone in the tree as compared to groups of birds. Finally, birds in same head colour morph groups had a higher frequency of head movements than birds in mixed head colour groups. Results indicate heightened vigilance with increased perception of predation risk (small waterholes, open exposed perch, when alone) but that social vigilance also played a role (group composition) with particularly the aggressive red-headed birds being more vigilant when together with other red-headed birds. Future research should investigate the effect of smaller waterholes as global warming will cause smaller waterholes to become more common for longer periods of time, which can increase stress in the birds.

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Habitat but not group size or recent predator activity affect corvid collective vigilance at carcasses

Cited by 3 publications

References 87 publications

Seasonal changes in herd size and time budget of springbok (Antidorcas marsupialis) in southern Namibia

Seasonal changes in herd size and time budget of springbok (Antidorcas marsupialis) in southern Namibia

Vertebrate scavenging in Australia is shaped by a complex interplay of bioregional, seasonal and habitat factors

Watch out! High vigilance at small waterholes when alone in open trees

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