Previous Nest Research Articles

Breeding and Natal Dispersal of the Goldeneye, Bucephala clangula

SUMMARY (1) Breeding and natal dispersal were examined for female goldeneye breeding in nest boxes in Sweden. Females changing nest box between years dispersed a median distance of 0 75 km to the new nest box (or, to the tenth nearest nest box). Individuals (N = 17) which returned to the natal area to breed, nested in the vicinity (median = 0 73 km) of the box in which they had hatched. (2) Neither the proportion of females changing nest box, nor the distances moved between nest boxes, varied among years. (3) Forty-two percent of females reoccupied the same nest box in successive years. Females which failed to breed successfully were less likely to return to the same nest box than females which bred successfully. (4) Females which moved to another nest box were less likely to hatch their broods successfully than females which returned to the same nest box. When they moved they produced smaller clutches and broods, and bred later in the season than when they returned to the same nest box. (5) Among females which moved, those which had failed to breed successfully moved further to another nest box than those which had bred successfully. In the case of females which lost clutches to predators, moving away from the vicinity of the previous nest box may have been advantageous, since boxes in which clutches were preyed-upon tended to be preyed-upon in the following year and also tended to occur close together. (6) The greater the distance from the previous nest box at which females bred, the less likely they were to start egglaying early in the season. (7) Females whose previous nest box was occupied by another female moved further to new nest boxes than females whose previous nest box was left empty.

Dispersal between Nest-Sites by Stonechats Saxicola torquata in Relation to Previous Breeding Success

Distances between nest-sites used successively within a breeding season were measured in a population of Stonechats. The frequencies and consequences of dispersing different distances were examined in relation to previous nesting success. Nestpredation tended to be greatest after moving far from the previous nest site, and was no higher after predation on the previous nest, but was low if many young had fledged. Nestling growth was significantly better at greater distances from the previous nest, if young had fledged from it. Birds moved farther, and were more likely to use different vegetation in which to nest, after previous predation than if success had been low for other reasons. After escaping predators, they moved farther, and were more likely to change vegetation, if more young had fledged from the previous nest. These results imply that birds adjust the placement of nests according to previous success, though great variation in dispersal distance remained unexplained by these tactics.

Breeding Biology and Development of the Young of Manorina Melanocephala, a Communally Breeding Honeyeater

The Noisy Miner is a communal breeder: many individuals participate in activities at each nest. However, much of the species’s behaviour and social organization is unique, even among communal breeders. Marked populations were observed in south-eastern Queensland between 1969 and 1974 but most data are from one intensely studied area in 1972, with additional data from 1971 and 1973.In this study area of seven hectares, 137 birds were colour-banded. The resident population declined in the three years from 9.0 to 7.7 birds per hectare. The sex ratio favoured males by as much as 3.3:1. Most breeding occurred between July and November. The onset of nesting varied from year to year and could not be easily related to environmental variables. Most nests were built in sites that did not afford much concealment. The height of nests varied but preference was mot shown by particular females. Successive nests tended to be higher, effected by females selecting higher trees. Spiders’ web and silk from cocoons was used in the construction of nests. The female built the nest and advertised its position with a flight display. Previous nests were dismantled and used in the construction of the nests. Building visits averaged 8.7 per hour and as many as seven males visited a nest at this stage. Females did not visit other nests. Males visiting the nest of an incubating female were all found to be producing spermatoza and at any time of year probably some males in a population are producing sperm. In some years some adult females made no nesting attempts.Clutches varied from one to four and averaged 2.64 eggs. The first egg was laid in fewer than three days or more than nine after completion of the nest. Eggs were laid one each day usually, in the early morning, and females began to sit after the second egg was laid. Only one female incubated and incubation took sixteen days. Attendance at the nest by females at different stages in incubation averaged from 35.2 to 41.2 minutes per hour.The mean brood size was 2.52; 15.9 per cent of eggs, excluding those lost, failed to hatch. The nestling period was about sixteen days. Only the female brooded.Fledging proceeded over several days, the young gradually moving out on supporting branches in the day and returning to the nest at night. Once away from the nest, the young made their way to the top of a tree. They were highly vocal in soliciting food. When fed, the wings were not quivered, perhaps a behaviour counteracting the high activity of feeding adults. Feeding rates at this stage were as high as 87.8 times per hour. Juveniles between twenty-six and thirty days from the nest were first threatened by adults. Between thirty-one and thirty-five days, they began to utter a quiet warbling subsong. Attacks by adults became more frequent and reached their greatest intensity between fifty and seventy days. Both males and females attacked juveniles.Nest success was very low, less than ten per cent in each of the three years. Even if some nests were never laid in, success calculated to exclude this possibility was still no greater than 16.7 per cent in any year. Some loss could be attributed to wind and storms; presumably the remainder was through predation or activities of the Miners themselves. A new nest was usually started when a female lost eggs or nestlings, in one case in fewer than sixty hours.

Some Measurements of Swallow Breeding Biology in Lowland Scotland

This Scottish study offers comparisons with a previous national Nest Record Card analysis based on mainly English data. In the north, clutches average larger and are laid later, and larger clutches are more successful. Within a clutch hatching appears not to be synchronised; and nestling growth rates are not correlated with brood size. The overall breeding success found in Lowland Scotland was 76.3%.

Breeding biology and conservation of Hawksbill turtles, Eretmochelys imbricata L., on Cousin Island, Seychelles

A two-year tagging programme on Cousin Island, Seychelles showed that Hawksbills nested between September and March, each female nesting on average four times at intervals of 15 to 18 days. Females did not nest in successive years but the number of years between breeding attempts is not known. Twenty to thirty females now nest each year; the number of nests has increased markedly since the island became a nature reserve in 1968. Some females tried to nest on other islands in the same season, although those returning to Cousin usually did so within 50 m of their previous nest. The average clutch was 182, the largest recorded for any sea turtle, and the maximum estimate of average nest success was 86%. Present exploitation in the Seychelles is unsound from both biological and sociological points of view, exploiting the vulnerable breeding stock for a luxury product (‘tortoiseshell’) while wasting potentially valuable protein. It is recommended that future policy should concentrate instead on harvesting eggs for human consumption, while totally protecting adults, thus diverting valuable protein from natural predators to the local human population. This policy would exploit the stage of the turtle's life cycle best adapted to sustain high losses with minimum effect on breeding stocks, to the mutual benefit of turtle and local human populations.

Dispersal Capacity of the Dusky-Footed Woodrat, Neotoma fuscipes

Fifty-eight individuals of Neotoma fuscipes were displaced an average of 1127 meters. The average distance moved by the 28 recovered animals from the release site was 885 meters. Approximately half of the recovered animals moved in a direction away from their previous nest sites. No evidence of homing was found. The highest rate of movement recorded was 1600 meters in five nights.