The influence of distance to refuge on flight initiation distance in the gray squirrel (Sciurus carolinensis)

1989 ◽  
Vol 67 (1) ◽  
pp. 233-235 ◽  
Author(s):  
Lawrence M. Dill ◽  
Robert Houtman
Keyword(s):  
Sciurus Carolinensis ◽  
Flight Initiation Distance ◽  
Gray Squirrel ◽  
Tree Squirrels ◽  
Flight Initiation ◽  
Model Predator

Gray squirrels (Sciurus carolinensis) typically run to the nearest tree to escape from predators they encounter while foraging on the ground. As the risk of capture increases with distance from the refuge tree, squirrels feeding far from trees should have greater flight initiation distances than those feeding closer by. This prediction was confirmed: flight initiation distance in response to a motorized model predator (a cat) increased as distance to refuge increased. This could not be attributed to any effect of distance to refuge on vigilance.

Effects of levels of human exposure on flight initiation distance and distance to refuge in foraging eastern gray squirrels (Sciurus carolinensis)

2011 ◽  
Vol 89 (9) ◽  
pp. 823-830 ◽  
Author(s):  
S.C. Engelhardt ◽  
R.B. Weladji
Keyword(s):  
Human Exposure ◽  
Sciurus Carolinensis ◽  
Flight Initiation Distance ◽  
Trade Offs ◽  
Decision Making Processes ◽  
Prey Escape ◽  
Exposure Levels ◽  
Escape Decision ◽  
Flight Initiation ◽  
Eastern Gray Squirrels

Flight initiation distance (FID), the distance at which an organism begins to flee from an approaching predator or threat, is associated to prey escape decision-making processes with benefit and cost trade-offs to remaining in a patch. Factors that may affect FID can be altered by human-stimulated predation risk, although the magnitude of response may depend on human exposure. We investigated how FID and distance to refuge of foraging eastern gray squirrels ( Sciurus carolinensis Gmelin, 1788), vary in seven sites corresponding to three levels of human exposure. We predicted that both FID and distance to refuge increase as exposure to human stimuli decreases; FID increases with the starting distance of the approaching human; and FID increases with distance to refuge. We found that FID increased with decreasing human exposure and that FID increased with increasing starting distance. We found no difference in distance to refuge between exposure levels. Our results suggest that risk posed to gray squirrels in areas frequently visited by humans is minimized or reduced, leading to differences in FID between exposure levels and may be attributed to habituation to increased nonlethal stimuli in the form of exposure to humans.

scholarly journals European birds adjust their flight initiation distance to road speed limits

2013 ◽  
Vol 9 (5) ◽  
pp. 20130417 ◽  
Author(s):  
Pierre Legagneux ◽  
Simon Ducatez
Keyword(s):  
Habitat Structure ◽  
Territory Size ◽  
Speed Limit ◽  
Vehicle Speed ◽  
Flight Initiation Distance ◽  
Speed Limits ◽  
Behavioural Responses ◽  
Road Speed ◽  
Flight Initiation ◽  
Local Speed

Behavioural responses can help species persist in habitats modified by humans. Roads and traffic greatly affect animals' mortality not only through habitat structure modifications but also through direct mortality owing to collisions. Although species are known to differ in their sensitivity to the risk of collision, whether individuals can change their behaviour in response to this is still unknown. Here, we tested whether common European birds changed their flight initiation distances (FIDs) in response to vehicles according to road speed limit (a known factor affecting killing rates on roads) and vehicle speed. We found that FID increased with speed limit, although vehicle speed had no effect. This suggests that birds adjust their flight distance to speed limit, which may reduce collision risks and decrease mortality maximizing the time allocated to foraging behaviours. Mobility and territory size are likely to affect an individuals' ability to respond adaptively to local speed limits.

Optic nerve head morphology of the Eastern gray squirrel, Sciurus carolinensis

2004 ◽  
Vol 7 (3) ◽  
pp. 169-173
Author(s):  
Lindsay A. Kuester ◽  
Andras M. Komaromy ◽  
Dennis E. Brooks ◽  
Patricia A. Lewis ◽  
Fred Bennett ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Optic Nerve Head ◽  
Sciurus Carolinensis ◽  
Gray Squirrel ◽  
Head Morphology ◽  
Eastern Gray Squirrel

scholarly journals Increasing corvid tolerance to humans in urban ecosystems with increasing latitude

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Nadezhda Poddubnaya ◽  
Tatyana Korotkova ◽  
Polina Vanicheva
Keyword(s):  
Environmental Factors ◽  
Human Disturbance ◽  
Urban Ecosystems ◽  
Flight Initiation Distance ◽  
Protection Measures ◽  
Non Invasive ◽  
Alert Distance ◽  
Behaviour Changes ◽  
Hooded Crows ◽  
Flight Initiation

The rapid growth of cities causes behaviour changes in birds in response to urban environmental factors. The avian response to human disturbance has recently been studied by a non-invasive research tool as an alert distance (AD) and a flight initiation distance (FID) assessment. The tolerance of hooded crows (n = 395), jackdaws (n = 394) and rooks (n = 169) to humans was assessed by AD and FID. It was shown that the FID of all species is maximal during the summer, when the parents send clear “danger—fly away” signals to the young and the birds fly away. The AD and FID of the three species reliably correlates with the season. Rooks showed FID species-specificity in seven cities of Eastern Europe. Comparison of the attitude of birds to people in cities that have similarities in human culture showed that tolerance increases with increasing latitude in all species and is statistically significant only in the jackdaw. This should be taken into account in environmental protection measures.

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