Does visibility influence owl peering behavior? Studies with Short-eared owls (Asio flammeus) and Northern Saw-whet owls (Aegolius acadicus)

AbstractAggressive behaviour of Montagu’s harrier was observed during the pre-laying period in the 1992–1995 seasons on the calcareous marshes of Chelm in Eastern Poland. In total, 435 flights performed by 24 pairs of individually marked harriers were analysed. All flights were performed in relation to the territory of defence. Males performed 61% of aggressive interactions while females performed 39%. Intraspecific and interspecific aggression comprising direct attacks (58%), escorts (13%), pursuits (28%) and “mirror behaviour” (1%) were described for the first time. Interspecific aggressive behaviour occurred only near territory boundaries. The main intruders were marsh harriers Circus aeruginosus breeding on the same marshes. Occasionally, harriers attacked curlews Numenius arquata, short-eared owls Asio flammeus, magpies Pica pica, hooded crows Corvus corone cornix, common buzzards Buteo buteo or hobbies Falco subbuteo. Four cases of communal mobbing were observed. Three to five males from the neighbourhood attacked the intruders together. Intraspecific aggressive behaviour was observed in the pair territory, near the boundary or at a distance of up to 100 m from the defended area. Aggressive interactions performed by both sexes were more frequent towards birds of the same sex. Females defended their territories more aggressively against females. Similarly, males were more aggressive against males. All cases of aggressive behaviour were observed near harrier territories. Aggressive relations between birds outside breeding territories or when foraging around marshes were not observed.

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Twenty-five year population trends in Northern Saw-whet Owl (Aegolius acadicus) in eastern North America

The Wilson Journal of Ornithology ◽

10.1676/19-125 ◽

2021 ◽

Vol 132 (3) ◽

Author(s):

Jennifer Wall ◽

David Brinker ◽

Scott Weidensaul ◽

David Okines ◽

Pascal Côté ◽

...

Keyword(s):

North America ◽

Population Trends ◽

Eastern North America ◽

Aegolius Acadicus

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Territorial Behavior of Short-eared Owls, Asio flammeus, at more than 1000 km North of their Current Breeding Range in Northeastern Canada: Evidence of Range Expansion?

The Canadian Field-Naturalist ◽

10.22621/cfn.v124i1.1032 ◽

2010 ◽

Vol 124 (1) ◽

pp. 58

Author(s):

Jean-François Therrien

Keyword(s):

Climate Change ◽

Range Expansion ◽

Territorial Behavior ◽

The Arctic ◽

Eastern Canada ◽

Breeding Range ◽

North Eastern ◽

Asio Flammeus

A pair of Short-eared Owls was observed throughout the summer of 2008 showing territorial behavior more than 1000 km north of their known breeding range in north-eastern Canada. These observations might be related to high lemming densities and/or climate change occurring in the Arctic.

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Winter Foraging Behavior of Short-eared Owls (Asio flammeus) in Ohio

The American Midland Naturalist ◽

10.2307/2425218 ◽

1983 ◽

Vol 110 (1) ◽

pp. 124 ◽

Cited By ~ 5

Author(s):

Bruce A. Colvin ◽

Steven R. Spaulding

Keyword(s):

Foraging Behavior ◽

Winter Foraging ◽

Asio Flammeus

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The developmental cycle of Caryospora bubonis Cawthorn and Stockdale 1981 (Protozoa: Eimeriidae) in the great horned owl, Bubo Virginianus (Gmelin)

Canadian Journal of Zoology ◽

10.1139/z82-019 ◽

1982 ◽

Vol 60 (2) ◽

pp. 152-157 ◽

Cited By ~ 19

Author(s):

Richard J. Cawthorn ◽

P. H. G. Stockdale

Keyword(s):

Prepatent Period ◽

Gallus Domesticus ◽

Endogenous Development ◽

Developmental Cycle ◽

Patent Period ◽

Bubo Virginianus ◽

Indirect Transmission ◽

Asio Flammeus ◽

Cross Transmission ◽

Transmission Studies

The purpose of the study was to describe some parameters of oocyst production in direct and indirect transmission studies, endogenous development, and attempts at cross transmission of Caryospora bubonis (Protozoa: Eimeriidae) of great horned owls, Bubo virginianus (Gmelin). Three great horned owls were given sporulated oocysts of C. bubonis orally. Three more great horned owls were each fed two mice which had been given sporulated oocysts of C. bubonis orally, 4 weeks previously. Feces were examined daily by flotation and daily oocyst production was estimated. One great horned owl was given sporulated oocysts of C. bubonis and killed 12 days after infection when oocysts were first detected in feces. Tissues were examined histologically. Two long-eared owls (Asio otus (Pontoppidan)) and one short-eared owl (Asio flammeus (L.)) and domestic chicks (Gallus domesticus L.) were given sporulated oocysts of C. bubonis orally and their feces examined as above. Mice were given varying doses of sporulated oocysts of C. bubonis orally and killed sequentially after infection. Tissues of mice and chickens were examined histologically.The prepatent period was 12 days, the patent period was 4–11 days long and maximal oocyst production occurred from 12 to 17 days after direct infection of great horned owls with C. bubonis. The prepatent period was shortened by 48 h in owls indirectly infected with C. bubonis in mice. Endogenous development occurred in the posterior third of the small intestine. Caryospora bubonis was not transmitted to other species of birds.

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