Resident Pairs Research Articles

NUMBERS OF MEADOW PIPITS ANTHUS PRATENSIS ON MOUNTAIN FARM GRASSLAND IN NORTH WALES IN THE BREEDING SEASON

SUMMARYOn c. 15 ha of mountain farm grassland in Wales, during 1972‐75, adult Meadow Pipits were present during March–September (but scarce in August–September). Breeding occurred during late April to late July. Incubation was performed by the female but both sexes fed the nestlings. Adults showed an average annual mortality of 54%.Adults spent nearly all their time on the ground, but varied in their activities and use of the habitat according to the stage of breeding. Their unobtrusive behaviour had a marked effect on the ease with which they could be observed for a population count. Males were seen on 30% of the days for which they were assumed to be present and were recorded giving song‐displays on 28% of the days when they were actually seen. We conclude that, to count all the birds present on a site, most must be marked, sightings must be carefully mapped and the number of observer days must be at least 20, preferably in April‐May.The numbers of individually marked (and a few unmarked) birds were determined by mapping them on large‐scale aerial photographs. This gave an average annual density of 48 resident pairs per km2. The average home range was 2.18 ha; this value remained relatively constant from year to year. At low population density individual home ranges were separated from one another, and there was some unoccupied ground, but at high population density the ranges overlapped with one another.

Changes in activity patterns, agonistic behavior, and territoriality of black ducks (Anas rubripes) during the breeding season in a Nova Scotia tidal marsh

Observations of marked wild black ducks provided a qualitative and quantitative description of hostile interactions between pairs throughout the breeding season. This study was carried out on a tidal estuary on the St. Lawrence estuary shore of Nova Scotia from 1972 to 1974. Interactions occurred first on the communal part of the marsh and later on territories.Territories corresponded to tidal ponds (0.16–3.8 ha) at the marsh periphery and were established only after pairs were on the marsh 30–40 days. Territories were established approximately 5 days before egg laying began and females were responsible for their location. Females spent approximately 45 days on the territory and males stayed 27–32 days. Males remained almost continuously on territories during the prelaying and laying periods but left both females and territories during midincubation.The activity of males and females of pairs was analysed and compared according to three activities: foraging, loafing, and hostility. Females foraged at a faster rate and for longer durations than their mates in both the preterritorial and territorial periods. Hostility by territorial males toward intruding pairs provided seclusion for resident pairs. Changes in the form and intensity of hostility led to the spatial displacement of pairs. The pursuit flight by males was the main mechanism in the establishment and maintenance of territories.

Social Behaviour of the Jackdaw, Cor Yus Moned Ula, in Relation To Its Niche

Social Behaviour of the Jackdaw, Cor Yus Moned Ula, in Relation To Its Niche

Effect of Social-Housing Conditions on Aggression in an Intruder-Resident Paradigm in Cavia Porcellus

The resident-intruder method was used to study the agonistic behavior of male guinea pigs. Resident animals were housed in male-male or male-female pairs, while male intruders were isolated or housed with another male. Intruders were introduced singly into the home cage of the resident pairs over six 30-min. test sessions. Residents won significantly more encounters than did intruders. Sexual composition of resident pairs did not affect aggressive behavior. Residents which met isolated intruders exhibited significantly more aggression than those which met socially maintained intruders. Aggressive behavior decreased during sessions, but did not change appreciably across sessions. These results are discussed in conjunction with other recent findings which emphasize the importance of aggression-evoking properties of the intruders’ behavior.

Fall Diet of Lesser Prairie Chickens in West Texas

Published accounts of feeding habits of the Roadrunner (Geococcyx californianus) (Zimmerman, Condor 72:475476. 1970: Binford. Calif. Birds 2:139. 1971) include the fact that the species is known to capture small birds on the ground. A. C. Bent (U.S. Natl. Mus. Bull. 176:45, 1940) briefly mentioned observations of the capture of a swift and a House Sparrow (Passer domesticus) in flight by Roadrunners, which leaped into the air from the ground. However, I find no detailed description in the literature of the aerial capture of a bird. On 28 April 1974, my husband and I were watching and photographing hummingbirds of several species at our window feeders in Portal, Arizona. We became aware that one of our resident pair of Roadrunners was crouched on the roof of a small porch nine feet above ground, just above the hummingbird feeders which hang from wires from the eaves (fig. 1). We had seen it on the ground below the feeders, occasionally leaping into the air in an unsuccessful attempt to catch a bird. Several times the Roadrunner changed position and made tentative passes at the birds. Suddenly it leaped off the roof and snapped up a Black-chinned Hummingbird (Archilochus alexan&) in flight, landing on the ground with the bird in its beak. I quickly took one picture and then we followed the bird as it ran off, but shortly lost it in brush. Forty minutes later I noted either this same Roadrunner or another running across the yard with another bird in its beak, this one sparrow-sized. The unusual aspect of this incident is that the Roadrunner attacked its flying prey from an elevated perch rather than the ground. On 20 June 1974, we saw a Roadrunner pounding something on the ground by our brush pile, where we have several sugar-water feeders for orioles and hummingbirds, hanging from low branches. We approached the Roadrunner, which ran a short distance and dropped its prey-a Black-chinned Hummingbird that died in less than a minute. We speculate that the Roadrunner caught this hummingbird by jumping into the air from the ground.

Home Range Defense in the Red Fox, Vulpes vulpes L.

This paper describes the home range defense behavior observed when nonresident male red foxes were introduced into established home ranges of resident male-female pairs. In 12 observation periods, four intruders were introduced to each of three mated pairs which had been given three weeks to acclimate to a 4.05-hectare, fenced enclosure. The residents centered their activities around a natural den and the frequency of intruder-resident encounters decreased rapidly with increasing distance from the den. The primary home range defense was continual harassment of the intruders by the resident males through agonistic displays and chases. Physical contact was rare. Even though the resident males were dominant in less than a majority of the interactions observed, they were usually successful in displacing the intruders within a few hours. The resident females seldom interacted with the intruders.

THE BREEDING BIOLOGY AND BEHAVIOUR OF THE REDWINGED STARLING ONYCHOGNATHUS MORIO.

Summary. 1 In the Cape the Redwinged Starling population consists of two parts: resident pairs and roving flocks. Pairs are territorial, usually roosting all year at the nest. Widowed males or females do not flock again, but quickly acquire new mates, in or out of the breeding season. 2 Flocks are probably composed mainly of juveniles, but with some sexually mature birds; incipient pairs may form in flocks. Flock movements, apparently related to changing food supplies, differ between areas but are broadly the same in any one area from year to year. They are conspicuous on the breeding grounds in the early breeding season. 3 Calls and territorial behaviour are described. Mirror experiments show that postures associated with preening have acquired significance as warning signals. The small territory (±2000 sq. yds.) is not used for feeding except incidentally. It is successfully defended against strange pairs, but not against flocks, which ignore pairs except during copulation. Other creatures (human beings, dogs, etc.) are boldly attacked near the nest, mainly during breeding but also at other times. 4 One method of pair-formation is described, but other methods must exist. 5 The male courts the female with food. The typical ceremony or parts of it may emerge in overt behaviour at inappropriate times. 6 Nest-site and building are described. 7 Two clutches are laid, normally in October and December; c/3 is usual, c/2 and c/4 fairly frequent. Eggs are laid on succeeding or alternate days. 8 Only the hen incubates and she starts sitting steadily before or with clutch completion. The apparent incubation period of earlier eggs may equal, or be up to 2 days longer or shorter than, that of the last egg. Periods for 14 clutches varied from 12½ to 23 days, average 16. In the same nests, fledging periods varied from 22 to 28 days, average 26. Thus the range of individual variation is 66% of the mean in incubation periods against 21% in fledging periods. 9 Hatching, brooding and development of the young are described. Observation and experiment showed that auditory stimuli release the gaping response in blind and also older nestlings. Behaviour at fledging is described, including an abnormal instance when the young were violently ejected by the male. 10 Breeding success is discussed and data supplied on food.

A STUDY OF THE BLACK CROW CORVUS CAPENSIS.

Summary. The habits of the Black Crow in Eastern Cape Province are described. Resident pairs are strongly territorial, but roving flocks feed over wide areas. Main breeding season is from August to November. Incubation period about 18 days, both parents sharing incubation. Nestling period about 38 days, both parents feeding young. Diet is very varied, e.g. vegetable matter, including seeds, fruits and bulbs; insect matter, especially dung‐beetles; vertebrates, such as amphibia and small chickens. Indigestible matter is regurgitated in pellets.