Clutch Size and Nesting Success in Red-Winged Blackbirds

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

Breeding Biology of the Savannah Sparrow on Kent Island

The Auk ◽  
1978 ◽  
Vol 95 (2) ◽  
pp. 235-246 ◽  
Author(s):  
Clara L. Dixon
Keyword(s):  
New Brunswick ◽  
Clutch Size ◽  
Breeding Season ◽  
Breeding Population ◽  
Nesting Success ◽  
Breeding Biology ◽  
Passerculus Sandwichensis ◽  
Herring Gulls ◽  
Savannah Sparrow ◽  
The Mean

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.

scholarly journals Effects of Brown-Headed Cowbirds on the Nesting Success of Chipping Sparrows in Southwest Colorado

The Condor ◽  
2001 ◽  
Vol 103 (1) ◽  
pp. 127-133 ◽  
Author(s):  
Catherine P. Ortega ◽  
Joseph C. Ortega
Keyword(s):  
Clutch Size ◽  
Molothrus Ater ◽  
Nesting Success ◽  
Nest Failure ◽  
Nest Concealment ◽  
Nest Placement ◽  
Spizella Passerina

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.

Reproductive variables of American black ducks along the St. Lawrence estuary, 1963-1991

1998 ◽  
Vol 76 (6) ◽  
pp. 1165-1173 ◽  
Author(s):  
Luc Bélanger ◽  
Austin Reed ◽  
Jean-Luc DesGranges
Keyword(s):  
Clutch Size ◽  
Nesting Success ◽  
Laying Date ◽  
Peat Bogs ◽  
Mixed Stands ◽  
Lawrence Estuary ◽  
Julian Date ◽  
Black Duck ◽  
American Black ◽  
St Lawrence Estuary

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.

Nesting parameters in a high density, declining population of blue grouse

1988 ◽  
Vol 66 (8) ◽  
pp. 1736-1741 ◽  
Author(s):  
Fred. C. Zwickel ◽  
Richard A. Lewis ◽  
Donald T. McKinnon
Keyword(s):  
British Columbia ◽  
Clutch Size ◽  
Nesting Success ◽  
Moderate Density ◽  
Egg Hatchability ◽  
General Region ◽  
Adult Females ◽  
Dendragapus Obscurus ◽  
Very High ◽  
Egg Fertility

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.

Is wedge-tailed eagle, Aquila audax, survival and breeding success closely linked to the abundance of European rabbits, Oryctolagus cuniculus?

2014 ◽  
Vol 41 (2) ◽  
pp. 95 ◽  
Author(s):  
Jerry Olsen ◽  
Brian Cooke ◽  
Susan Trost ◽  
David Judge
Keyword(s):  
Biological Control ◽  
Clutch Size ◽  
Oryctolagus Cuniculus ◽  
Biological Control Agent ◽  
Control Agent ◽  
Nesting Success ◽  
Natural Ecosystems ◽  
Continental Scale ◽  
Rabbit Haemorrhagic Disease ◽  
Haemorrhagic Disease

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.

scholarly journals THE EFFECTS OF WEATHER AND REED MANAGEMENT ON NESTING PARAMETERS OF THE GREAT REED WARBLER, ACROCEPHALUS ARUNDINACEUS (AVES: SYLVIIDAE)

2016 ◽  
Vol 7 ◽  
pp. 305-312
Author(s):  
Thomas Oliver Mérő ◽  
Antun Žuljević
Keyword(s):  
Clutch Size ◽  
Water Depth ◽  
Abiotic Factors ◽  
Negative Relationship ◽  
Nesting Success ◽  
Great Reed Warbler ◽  
Nest Density ◽  
Hatching Rate ◽  
Reed Warbler ◽  
The Impact

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.

scholarly journals A Comparison of the Characteristics and Fate of Barrow's Goldeneye and Bufflehead Nests in Nest Boxes and Natural Cavities

The Condor ◽  
2002 ◽  
Vol 104 (3) ◽  
pp. 610-619 ◽  
Author(s):  
Matthew R. Evans ◽  
David B. Lank ◽  
W. Sean Boyd ◽  
Fred Cooke
Keyword(s):  
Clutch Size ◽  
Canopy Cover ◽  
Forest Edge ◽  
Nesting Success ◽  
The Other ◽  
Nesting Ecology ◽  
Nest Boxes ◽  
Cavity Nesting ◽  
Bucephala Islandica ◽  
Cavity Nests

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.

scholarly journals Demography, breeding success and effects of nest type in artificial colonies of Red-footed Falcons and allies

2015 ◽  
Vol 23 (1) ◽  
pp. 1-21 ◽  
Author(s):  
László Kotymán ◽  
Szabolcs Solt ◽  
Éva Horváth ◽  
Péter Palatitz ◽  
Péter Fehérvári
Keyword(s):  
Clutch Size ◽  
Reproductive Performance ◽  
Nesting Success ◽  
Limiting Factor ◽  
Artificial Nests ◽  
Breeding Sites ◽  
Nest Box ◽  
Nest Boxes ◽  
Artificial Breeding ◽  
Nest Type

Abstract Shortage of breeding sites is an important limiting factor of bird populations. Artificial breeding platforms, nest-boxes or man-made twig nests often present solutions with remarkable results, however long-term sustainability of these populations remains to be resolved. Furthermore, the question whether the inference of results of studies conducted on birds breeding in artificial breeding sites can be generalized to other populations, still remains open. Here we present the history, and the results of a 20 year old (1995-2015) nest-box programme initiated to increase potential breeding possibilities of Red-footed Falcons in an area, where nest-site shortage was a severe limiting factor. We show how various other species (Jackdaws, Kestrels and Long-eared Owls) have utilized these resources, and present descriptive statistics on their reproductive performance. Analysing the data of a total of 1432 breeding attempts, we show that Red-footed Falcons have similar clutch sizes, and nesting success (i.e. ratio of nests with at least on fledgling), however fledging success (ratio of the number of eggs/fledged nestlings) was different in artificial nest-boxes. When we excluded closed box types from artificial nests, this difference was not apparent. In case of Kestrels (n=1626 breeding attempts) clutch size was significantly higher in artificial nests, while we found no difference in fledging or nesting success. When only comparing open boxes to natural nests, the difference in clutch size was no longer significant. We also analysed the effect of nest box design on reproductive parameters of the two species using regression trees. Inter annual effects were the most important in shaping clutch size and fledging rate of both falcon species, however we also found nest-box design effects, but only in Red-footed Falcons. In years when mean clutch size was high, these birds had lower clutch size in an older, darker nest-box type compared to an alternative design, and to open boxes. However, fledging rate in the same years was lower for both open boxes and older nest-boxes. We conclude that artificial colonies are an important and successful tool in Red-footed Falcon conservation, and that the breeding parameters measured in artificial colonies depend on nest-box design. We present correlative evidence that closed boxes have a significant positive species specific effect on reproduction, probably due to their protection against weather. We also show that birds may have a preference for a certain nest-box design, and that the breeding success in the less favoured box type may be similar to that in open nests. We recommend that future studies incorporate nest-type and nest-box design effects in all comparisons made on reproductive performance in case of Red-footed Falcons and Kestrels.

scholarly journals Nesting Ecology of West African Dwarf Crocodiles in a Heavily Disturbed Landscape in Chirehin, Ghana

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Emmanuel Amoah ◽  
Emmanuel Danquah ◽  
James Perran Ross
Keyword(s):  
Ambient Temperature ◽  
Clutch Size ◽  
Incubation Temperature ◽  
West African ◽  
Nesting Success ◽  
Nest Temperature ◽  
Nesting Ecology ◽  
Forest Patches ◽  
West African Dwarf ◽  
Monitor Lizard

West African dwarf crocodiles (Osteolaemus sp. nov. cf. tetraspis) are among the most threatened crocodilians in the world due to unregulated hunting and habitat loss-related population decline. Despite this, many questions about their basic ecology remain unanswered and this inadequate data hampers effective dwarf crocodile management. We describe incubation temperature, nesting success, hatching rate, and clutch size of West African dwarf crocodiles. We monitored 18 nests from the 2017 and 2018 nesting seasons in the Chirehin Community Land—a highly disturbed agricultural matrix in the climatic transition zone of Ghana. We used Hobo tidbit® data loggers to monitor egg chamber temperature and the effect of ambient temperature on nest temperature. The daily mean incubation temperature recorded during the study was 30.7°C (±SD = 0.8°C, n = 240, range = 28–33°C) and it is congruent with the reported value for the species. The findings from this study suggest a weak positive to no correlation between dwarf crocodile incubation temperature and ambient temperature indicating nest temperature is almost independent of ambient temperature. We found a mean clutch size of 8 eggs per nest (SD = ±2; range = 5–13; n = 17) supporting previous reports that this genus has a low clutch size. The mean nesting success and hatching success across the two seasons were 77.8% and 75.3% (SD = ±41.9, n = 18), respectively. Three nests were destroyed by flood and one by an unknown predator suspected to be a West African Nile monitor lizard. Generally, dwarf crocodiles selected forest patches within the highly disturbed landscape for nesting indicating the need to protect the remaining forest patches. Efforts should be made to repeat the study across this species’ range for an improved understanding of its nesting ecology.

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