Effects of clutch size manipulations on reproductive behaviour and nesting success in the cooperatively breeding Bell Miner (Manorina melanophrys)

1993 ◽  
Vol 7 (4) ◽  
pp. 329-356 ◽  
Author(s):  
Aldo Poiani
2008 ◽  
Vol 4 (6) ◽  
pp. 606-609 ◽  
Author(s):  
Dik Heg

Suppression by dominants of female subordinate reproduction has been found in many vertebrate social groups, but has rarely been shown experimentally. Here experimental evidence is provided for reproductive suppression in the group-living Lake Tanganyika cichlid Neolamprologus pulcher . Within groups of three unrelated females, suppression was due to medium- and small-sized females laying less frequently compared with large females, and compared with medium females in control pairs. Clutch size and average egg mass of all females depended on body size, but not on rank. In a second step, a large female was removed from the group and a very small female was added to keep the group size constant. The medium females immediately seized the dominant breeding position in the group and started to reproduce as frequently as control pairs, whereas clutch size and egg mass did not change. These results show that female subordinate cichlids are reproductively capable, but apparently suppressed with respect to egg laying. Nevertheless, some reproduction is tolerated, possibly to ensure continued alloparental care by subordinate females.


The Auk ◽  
1975 ◽  
Vol 92 (4) ◽  
pp. 815-817
Author(s):  
William J. Francis
Keyword(s):  

The Auk ◽  
1978 ◽  
Vol 95 (2) ◽  
pp. 235-246 ◽  
Author(s):  
Clara L. Dixon

Abstract I studied the breeding biology of the Savannah Sparrow (Passerculus sandwichensis) on Kent Island, New Brunswick, Canada from 1964 through 1968. I estimated the breeding population to be 125-135 pairs $(412-445\ \text{individuals}/{\rm km}^{2})$. The mean number of nests produced per female, including those destroyed by predators, was 2.97. Clutch size ranged from 2 to 5. The mean clutch size based on 1,142 eggs in 284 nests of known clutch size was 4.02. Not only was the four-egg clutch most numerous but a greater percentage of eggs in the four-egg clutches hatched and the mean number of young fledged per nest was also highest. The mean incubation period was 12.2 days, the mean duration of nestling life was 9 days, and the approximate length of the breeding season as 52 days. The daily mortality rate of eggs was 11.9% and of nestlings 2.1%. Predation was the major factor affecting reproductive success; 50.5% of all nests located were destroyed by predators. The main nest predators were Common Crows and Herring Gulls. Of the nests destroyed by predators, 87.8% contained eggs rather than nestlings. The intense predation necessitated high nest replacement. The mean interval between the termination of one nest and the appearance of the first egg in the succeeding nest was 6.3 days. If successive nests are destroyed on the day incubation begins, it is hypothetically possible for a pair to produce four nests during a single breeding season; many birds in the population produce at least three. Although enough time was available for birds to fledge two broods in a season, few of them fledged more than one. Thus, the nesting success was low (success from egg to hatching 18.1%). High nest replacement compensated for high egg mortality, and an average of 2.16 young per pair were fledged per season.


The Condor ◽  
2001 ◽  
Vol 103 (1) ◽  
pp. 127-133 ◽  
Author(s):  
Catherine P. Ortega ◽  
Joseph C. Ortega

AbstractWe documented effects of Brown-headed Cowbird (Molothrus ater) parasitism on Chipping Sparrows (Spizella passerina) in southwest Colorado. Overall, 17 of 77 nests (22%) were parasitized. Abandonment was significantly higher among parasitized nests (29%) than unparasitized nests (5%). More Chipping Sparrows hatched and fledged per unparasitized nest than per parasitized nest. Reduction of host hatching and fledging rates in parasitized nests was attributable to smaller clutch size and higher abandonment. The major source of nest failure was predation, not parasitism; overall, 53% failed from predation, and only 6% failed from parasitism. There were no differences in weight, ulna length, tarsometatarsus length, or length of outermost primary between sparrow nestlings in parasitized and unparasitized nests. Only 18% of cowbird eggs laid resulted in a fledged cowbird. We observed no differences in nest placement or nest concealment between unparasitized and parasitized nests.


1998 ◽  
Vol 76 (6) ◽  
pp. 1165-1173 ◽  
Author(s):  
Luc Bélanger ◽  
Austin Reed ◽  
Jean-Luc DesGranges

We examine data from different surveys conducted from 1963 to 1991 in the Baie de l’Isle Verte National WildlifeArea and the surrounding offshore islands, an approximately 20-km2 coastal segment of the St.Lawrence estuary in Quebec.We summarize data regarding various aspects of the nesting ecology of the American black duck (Anas rubripes) (n = 812nests). Mean laying date, average clutch size, and apparent nesting success did not differ among years (P > 0.05). Black ducksnested earlier on islands (mean Julian date 120.0 vs. 121.3;P = 0.03), but mean clutch size and nesting success on islands didnot differ from those on the mainland (P> 0.05). Among mainland-nesting black ducks, those nesting in mixed stands of treesand bushes initiated nests almost 10 days earlier than those nesting in the two other types of nest cover (mean Julian date 124.0vs. 134.4 and 139.6). Black ducks nesting in such habitats as woodlots, peat bogs, or shrubland laid a larger number of eggsthan those nesting in the two other habitat types (mean 9.7 vs. 8.8 and 9.4). Finally, we observed that nesting success of ducksnesting in woodlots, peat bogs, and shrubland and in mixed stands of trees and bushes or of herbaceous plants and shrubs wasup to three times higher than at other sites (P<= 0.05). We conclude that in addition to protection and restoration of existingislands, more emphasis should be placed on conserving peat bogs, coniferous woodlots, and shrubland, because they alsoconstitute good mainland-nesting habitat for black ducks along the St. Lawrence estuary.


1988 ◽  
Vol 66 (8) ◽  
pp. 1736-1741 ◽  
Author(s):  
Fred. C. Zwickel ◽  
Richard A. Lewis ◽  
Donald T. McKinnon

Of four nesting parameters (clutch size, egg fertility, egg hatchability, and nesting success) in a population of blue grouse, Dendragapus obscurus fuliginosus, at Hardwicke Island, British Columbia, only clutch size differed between yearling and adult females. There was no difference among years for any of the parameters considered. This population declined from very high to moderate density during the studies reported here, and clutch size, egg fertility, and hatchability were significantly lower than reported for a more stable population (Comox Burn) in the same general region. Nesting success at Hardwicke Island, however, was higher than at Comox Burn. Collectively, the parameters examined do not, by themselves, explain the observed decline. Nevertheless, they suggest that the population at Hardwicke Island differed from that at Comox Burn in some fundamental aspects of reproduction that may be symptomatic of other factors possibly involved in its decline, e.g., the survival of chicks.


2014 ◽  
Vol 41 (2) ◽  
pp. 95 ◽  
Author(s):  
Jerry Olsen ◽  
Brian Cooke ◽  
Susan Trost ◽  
David Judge

Context Some ecologists argue that nesting success and abundance of wedge-tailed eagles (Aquila audax) are strongly linked to the abundance of introduced wild rabbits (Oryctolagus cuniculus). Consequently, concerns were expressed about eagle population viability when the biological control agent rabbit haemorrhagic disease virus (RHDV) heavily reduced rabbit numbers. However, observations following the spread of rabbit haemorrhagic disease (RHD) in Australia and Spain (where Aquila adalberti is an equivalent of A. audax) question this assertion. Eagle numbers did not fall even though rabbits declined regionally by up to 90% in both countries. Aims To reconsider the assumption of a strong link between rabbit abundance and wedge-tailed eagle breeding and population maintenance. Dispelling misconceptions, if any, about the eagles’ dependence on rabbits would benefit the future management of both eagles and rabbits. Methods We reviewed the literature associated with claims that eagles were heavily dependent on rabbits and asked whether these views could be substantiated given the lack of changes in eagle abundance following the spread of RHD. Data on eagle egg-clutch size and nesting success were also reviewed. Conclusions There is little evidence that eagles depend heavily on rabbits as prey. Instead, as rabbits decline, more kangaroos, reptiles and birds are eaten, partly because more native prey becomes available. Eagles have a high proportion of rabbits in their diets mainly where degradation of natural ecosystems, including that caused by rabbits, results in native prey being rare or unavailable. There has been minimal variation in average clutch size following major perturbations in rabbit population size. Implications Rather than perpetuating the idea that high populations of rabbits are needed for wedge-tailed eagle conservation, resources would be better re-directed into understanding continental-scale eagle population dynamics. This would provide a more rational framework to assist decisions on future biological control agents for rabbits.


1981 ◽  
Vol 2 (2) ◽  
pp. 97-105 ◽  
Author(s):  
Marc Alcher

AbstractThis paper reports some observations on the reproductive behaviour of captive Sardinian Brook Salamanders (Euproctus platycephalus). Amplexus was observed frequently from October to May; eggs were preferentially deposited between stones ofvarious sizes or burried in the sand; egg-laying was spread over several months and had a maximum in spring; clutch size was hight (maximum: 221) as compared to that of the closely related species E. montanus and E. asper.


2016 ◽  
Vol 7 ◽  
pp. 305-312
Author(s):  
Thomas Oliver Mérő ◽  
Antun Žuljević

Nesting parameters such as clutch size, hatching rate or nesting success have been extensively studied in birds in relation to biotic and abiotic factors. In this study we aimed to investigate the effects of air temperature, amount of precipitation, reed burning, and water depth (independent variables) on nest density, clutch size, hatching rate, and nesting success (dependent variables) of the Great Reed Warbler during a nine-year period. We found that neither the clutch size nor the hatching rate was influenced by any of the predictor variables. Nest density was positively influenced by the water depth, while the nesting success was negatively related to the amount of precipitation. Reed burning had no effect on any of the nesting parameters. Similarly, to our results, short-term studies reported a positive relationship between nest density and water depth, and a negative relationship between the nesting success and amount of precipitation, indicating that these two environmental variables generally influence the two nesting parameters. However, the impact of various reed management practices, such as harvesting or removal, on the nesting variables of the Great Reed Warbler needs further clarification.


The Condor ◽  
2002 ◽  
Vol 104 (3) ◽  
pp. 610-619 ◽  
Author(s):  
Matthew R. Evans ◽  
David B. Lank ◽  
W. Sean Boyd ◽  
Fred Cooke

Abstract Barrow's Goldeneye (Bucephala islandica) and Bufflehead (B. albeola) are cavity-nesting waterfowl that have received considerable attention in studies using nest boxes, but little is known about their nesting ecology in natural cavities. We found larger clutch size, lower nesting success, and different major predators for Barrow's Goldeneyes nesting in boxes versus those nesting in natural cavities, but few differences for Bufflehead. These differences are attributed to the location and physical differences between Barrow's Goldeneye nest boxes and natural cavities that affect their conspicuousness to predators and conspecific nest-parasitizing females. Goldeneye boxes were concentrated in highly visible locations such as trees at water or forest edge. Natural cavity nests, on the other hand, were often abandoned Pileated Woodpecker (Dryocopus pileatus) cavities, which were more dispersed throughout the forest interior and concealed under dense canopy cover. Bufflehead natural cavity nests were typically closer to edges, which may account for their similarity with boxes. We conclude that in some respects, studies of Barrow's Goldeneye that use nest boxes may not be representative of birds nesting in natural cavities, whereas those of Bufflehead are more likely to be so. Comparación de la Ecología de Nidificación de Bucephala islandica y B. albeola en Nidos Artificiales y en Cavidades Naturales Resumen. Los especies de patos Bucephala islandica y B. albeola anidan en cavidades, por lo que con frecuencia han sido estudiadas usando nidos articificales, pero poco se conoce sobre su ecología de nidificación en cavidades naturales. Los individuos de B. islandica que anidan en nidos artificiales presentaron nidadas más grandes, menor éxito reproductivo y distintos depredadores que los individuos que anidan en cavidades naturales, pero detectamos pocas diferencias para B. albeola. Estas diferencias son atribuidas a la ubicación y a las diferencias físicas entre los nidos artificiales y las cavidades naturales de B. islandica que afectan su visibilidad para deprededores y hembras coespecíficas que parasitan los nidos. Los nidos artificiales de B. islandica estuvieron concentrados en lugares muy visibles como árboles al borde del bosque o a la orilla del agua. Por el contrario, las cavidades naturales frecuentemente fueron cavidades abandonadas de Dryocopus pileatus, las cuales se presentaron más dispersas por el interior del bosque y ocultas bajo un dosel denso. Las cavidades naturales de B. albeola se ubicaron típicamente más cerca del borde, lo que tal vez explica la semejanza con los nidos artificiales. Concluimos que en algunos casos, los estudios de B. islandica que utilizan nidos artificiales pueden no ser representativos de individuos que anidan en cavidades naturales, mientras que los estudios de B. albeola probablemente sí sean más representativos.


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