Breeding ecology of the gadwall at Waterhen Marsh, Saskatchewan

1983 ◽  
Vol 61 (7) ◽  
pp. 1532-1539 ◽  
Author(s):  
James E. Hines ◽  
George J. Mitchell
Keyword(s):  
Brood Size ◽  
Open Water ◽  
Nesting Success ◽  
Breeding Ecology ◽  
Avian Predators ◽  
Mammalian Predators ◽  
Anas Strepera ◽  
Island Habitats ◽  
Very High ◽  
Nest Initiation

The nesting and brood ecology of the gadwall (Anas strepera) was studied at Waterhen Marsh, Saskatchewan, during 1972 and 1973. Prior to nesting, breeding pairs dispersed over the marsh in relation to the interspersion of open water and cover but later aggregated their nests in the safest insular habitats. The peak of nest initiation was late May and early June, while the peak of hatching occurred in early to mid-July. Early clutches (N = 295), initiated before June 20, averaged 10.37 ± 0.08 (± SE) eggs and late clutches (N = 27) averaged 8.00 ± 0.19 eggs. Nest densities and nesting success varied greatly between upland, ditchbank, and island habitats. Much of the variation in nesting success was caused by differences in the rate of mammalian predation between areas. Nest failure was attributed to desertion (9%), avian predators (9%), mammalian predators (4%), and unidentified predators (3%). An average of 9.97 ± 0.17 ducklings hatched from 260 successful clutches, but mean brood size decreased by 45% to 5.44 ± 0.50 (N = 9) by the time of flight. The overall productivity of Waterhen Marsh gadwalls was very high. Gadwalls breed later than do other ducks and thus gain several possible benefits including avoidance of competition and higher nesting success.

Factors affecting brood abandonment in gadwalls (Anas strepera)

2000 ◽  
Vol 78 (2) ◽  
pp. 327-331 ◽  
Author(s):  
Michel Gendron ◽  
Robert G Clark
Keyword(s):  
Body Condition ◽  
Brood Size ◽  
Female Body ◽  
Confounding Factor ◽  
Factors Affecting ◽  
Proximate Factors ◽  
Anas Strepera ◽  
Brood Desertion ◽  
Brood Success

Brood desertion by radio-equipped female gadwalls (Anas strepera) was examined to test three hypotheses regarding proximate factors responsible for post hatch brood abandonment in waterfowl. Gadwall broods with the greatest duckling mortality, independent of brood size, were more likely to be abandoned, providing support for the "brood-success" hypothesis. Our results do not support the "brood-size" hypothesis, as the size of broods immediately prior to female abandonment was no smaller than the size of broods not abandoned. Although brood fate was not related to female body condition, the "salvage-strategy" hypothesis could not be rejected, because experience was a confounding factor and could not be sampled adequately; younger, possibly less-experienced females were more likely to abandon their broods than older females. Further studies, preferably involving experimental manipulations, are needed to adequately address the full array of hypotheses.

scholarly journals Effect of habitat complexity on the distribution of Ceriodaphnia quadrangula (O. F. Müller, 1785) (Crustacea: Cladocera) in a deep lake

2010 ◽  
Vol 47 (2) ◽  
pp. 51-58 ◽  
Author(s):  
Małgorzata Adamczuk
Keyword(s):  
Surface Layer ◽  
Brood Size ◽  
Habitat Complexity ◽  
Littoral Zone ◽  
Open Water ◽  
The Other ◽  
Pelagic Zone ◽  
Submerged Vegetation ◽  
Deep Lake ◽  
Ceriodaphnia Quadrangula

Effect of habitat complexity on the distribution of Ceriodaphnia quadrangula (O. F. Müller, 1785) (Crustacea: Cladocera) in a deep lake The aim of the study was to compare the density, body size, and reproduction of the cladoceran, Ceriodaphnia quadrangula (O. F. Müller, 1785), in various habitats of Lake Piaseczno (38.8 m deep) in eastern Poland. Samples were taken in the littoral zone (from emergent and submerged vegetation, as well as from open water and the surface layer of water above submerged vegetation) and in the pelagic zone (from the epilimnion, metalimnion, and hypolimnion). The results show that C. quadrangula prefers the littoral zone, as it achieves there much higher values of the analysed variables than in the pelagic zone. The number and size of adults (including ovigerous females), as well as brood size achieved equally high values in emergent and submerged vegetation, and much lower values in the other habitats (including pelagic ones). Juveniles also preferred to stay in the littoral zone but displayed clear preferences to none of the habitats.

scholarly journals Nesting Success and Nesting Height in the Critically Endangered Medium Tree Finch (Camarhynchus pauper)

Birds ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 427-444
Author(s):  
Sonia Kleindorfer ◽  
Lauren K. Common ◽  
Petra Sumasgutner
Keyword(s):  
Rattus Rattus ◽  
Nesting Success ◽  
Trophic Levels ◽  
Critically Endangered ◽  
Fledging Success ◽  
Island Endemic ◽  
Galapagos Archipelago ◽  
Black Rat ◽  
Avian Predators ◽  
Fly Larvae

When different introduced species across trophic levels (parasite, predator) invade island systems, they may pose significant threats to nesting birds. In this study, we measure nesting height and infer causes of offspring mortality in the critically endangered Medium Tree Finch (Camarhynchus pauper), an island endemic restricted to Floreana Island on the Galápagos Archipelago. Considering all nests at which a male built a nest, sang and attempted to attract a female (n = 222 nests), only 10.4% of nests produced fledglings (5% of nests had total fledging success, 5.4% of nests had partial fledging success). Of the 123 nests chosen by a female, 18.7% produced fledglings and of 337 eggs laid, 13.4% produced fledglings. Pairing success was higher for older males, but male age did not predict nesting success. All nests with chicks were infested with avian vampire fly larvae (Philornis downsi). We attributed the cause of death to avian vampire fly if chicks were found dead in the nest with fly larvae or pupae (45%) present. We inferred avian (either Asio flammeus galapagoensis or Crotophaga ani) predation (24%) if the nest was empty but dishevelled; and black rat (Rattus rattus) predation (20%) if the nest was empty but undamaged. According to these criteria, the highest nests were depredated by avian predators, the lowest nests by rats, and intermediate nests failed because of avian vampire fly larvae. In conclusion, there is no safe nesting height on Floreana Island under current conditions of threats from two trophic levels (introduced parasitic dipteran, introduced mammalian/avian predators; with Galápagos Short-Eared Owls being the only native predator in the system).

Breeding Ecology and Nesting Success of Abbott's Babbler (Malacocincla abbotti)

2004 ◽  
Vol 116 (3) ◽  
pp. 275-277 ◽  
Author(s):  
Andrew J. Pierce ◽  
Korakoch Pobprasert ◽  
George A. Gale
Keyword(s):  
Nesting Success ◽  
Breeding Ecology

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.

Breeding biology of the red-capped robin

2003 ◽  
Vol 51 (6) ◽  
pp. 533 ◽  
Author(s):  
Damian K. Dowling
Keyword(s):  
National Park ◽  
Predation Rate ◽  
Nesting Success ◽  
Breeding Biology ◽  
Laying Date ◽  
Breeding Ecology ◽  
Incubation Periods ◽  
Almost All ◽  
Breeding Seasons ◽  
Semi Arid

The breeding biology of the red-capped robin (Petroica goodenovii) (Petroicidae) was studied over two breeding seasons (2000–02) in Terrick Terrick National Park, Victoria. Breeding commenced in August and the last offspring fledged in January. Only females developed brood patches, built nests and incubated. However, both sexes fed the young. Clutch size ranged from one to three eggs, with a mean of 2.1, with clutches of three occurring relatively early in the season. For clutches of two, the period from laying of the first egg to hatching was 14 or 15 days, with a mean of 14.2. The time from hatching to fledging was 13–15 days, with a mean of 14. In all, 34% of nesting attempts successfully fledged offspring. On average, 0.62 fledglings were produced per nesting attempt, whilst 0.57 offspring reached independence. Nesting success peaked in October. Predation appears to be responsible for almost all nest failure, and predation rate varied over the season. Breeding pairs produced 0–3 broods per season (0–5 independent fledglings) and pairs that began nesting early in the season produced a greater number of independent offspring. Nestling weight was affected by both laying date and brood size. A comparative analysis within the Petroicidae, controlled for body size, revealed that species endemic to Australia have shorter incubation periods, and species from semi-arid and dry woodlands have longer incubation periods than other species. Findings from this study are discussed in relation to the breeding ecology of other members of the Petroicidae.

Changes in the Distribution of Aquatic Plants in a Tropical Swamp

1983 ◽  
Vol 10 (4) ◽  
pp. 323-329 ◽  
Author(s):  
Patrick L. Osborne ◽  
Gregory J. Leach
Keyword(s):  
Papua New Guinea ◽  
Environmental Changes ◽  
Open Water ◽  
Emergent Vegetation ◽  
Aerial Photographs ◽  
Sewage Effluent ◽  
Tropical Wetlands ◽  
Ecological Importance ◽  
Port Moresby ◽  
Very High

Tropical wetlands are of great ecological importance and are worthy of widespread and vigorous conservation efforts. They are, however, very susceptible to environmental changes which often result from human activities. Waigani swamp near Port Moresby, Papua New Guinea, comprises a number of small, shallow lakes, the largest of which, Waigani Lake, has a surface area of 120 ha. This Lake now has nutrient-rich water with very high phytoplankton populations owing to sewage effluent disposal.Changes in the macrophyte flora and vegetation of Waigani Lake are documented in aerial photographs taken between 1942 and 1981. From 1942 to 1956 the Lake was dominated by emergent vegetation, and there was very little open water. Between 1956 and 1966 this emergent vegetation was replaced by dense stands of nymphaeids. In 1965, sewage disposal into Waigani Lake began and by 1974 only a few small stands of nymphaeids remained. By 1978 no nymphaeids could be found in Waigani Lake. The decline in the nymphaeid cover of Waigani Lake was accompanied by a regression of the surrounding reed-swamp. Two other lakes near Port Moresby are nutrient-poor and have a dominant and diverse macrophyte flora, being probably more comparable with Waigani Lake prior to its enrichment—apart from a recent takeover by a pestiferous free-floating water-fern.

scholarly journals The Influence of Biological Factors on Haematological Values in Wild Marsh Harrier (Circus aeruginosus) Nestlings

Animals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2539
Author(s):  
Urszula Zaremba ◽  
Zbigniew Kasprzykowski ◽  
Elżbieta Kondera
Keyword(s):  
Blood Cell ◽  
Cell Count ◽  
Mixed Models ◽  
Brood Size ◽  
Linear Mixed Models ◽  
Brood Reduction ◽  
Blood Cell Count ◽  
Marsh Harrier ◽  
Circus Aeruginosus ◽  
Nest Initiation

Marsh harrier (Circus aeruginosus) is a species with obligatory cainism, in which hatching asynchrony creates a pronounced size hierarchy in nestlings. The size-related competitive advantage of older nestlings means that they tend to dominate the younger ones, and brood reduction occurs in most nests. The aim of the study was to reference values and carry out a haematological examination in order to evaluate the physiological status and health of nestlings with respect to hatching order, brood size, and nest initiation date. To do so, we examined 19 nests with a total of 58 nestlings from a free-living population of this species located in fishpond complexes in the agricultural landscape of eastern Poland. Repeated blood samples (118 in all) were collected from nestlings. The following parameters were measured using fresh full blood: red blood cell count (RBC), haemoglobin level (Hb), white blood cell count (WBC), and plasma glucose level (Glu). The data were analysed using generalized linear mixed models and linear mixed models ((G)LMM). The study revealed that hatching order, but not brood size or nest initiation date, affected the physical condition of marsh harrier nestlings. Hb levels and RBC counts gradually decreased, whereas Glu levels and WBC counts increased from the first- to the last-hatched nestlings. This result points to the generally poorer condition of the youngest nestlings compared with their older siblings. The poor physiological condition of the youngest nestlings may consequently increase the likelihood of their perishing, and hence, of brood reduction.

scholarly journals Visual and Olfactory Attributes of Artificial Nests

The Auk ◽  
2000 ◽  
Vol 117 (1) ◽  
pp. 136-146 ◽  
Author(s):  
Sheila A. Rangen ◽  
Robert G. Clark ◽  
Keith A. Hobson
Keyword(s):  
Small Mammals ◽  
Nest Predation ◽  
Olfactory Cues ◽  
Deer Mice ◽  
Artificial Nests ◽  
Avian Predators ◽  
Mammalian Predators ◽  
Methodological Considerations ◽  
Time Required ◽  
Weak Tendency

Abstract Artificial nests are commonly used to investigate relative rates of nest predation in birds, but several methodological considerations need to be addressed before results from natural and artificial nests can be compared. Using field and laboratory experiments, we examined responses of predators to visual and olfactory cues that were associated with wicker nests and their contents. Avian predators did not discriminate between wicker nests dipped in mud and those covered by a camouflage fabric, whereas mammalian predators showed a weak tendency to depredate camouflaged nests. Nests containing plasticine eggs were depredated more often than nests containing only quail eggs and finch eggs, although no response to number of plasticine eggs in nests was found. The higher predation of nests with plasticine eggs may have resulted because small mammals, relying on olfactory cues, comprised a large portion of the predator assemblage. Field results were supported in tests where captive deer mice (Peromyscus maniculatus) were attracted to assortments of egg types that included plasticine. Time required by captive deer mice to penetrate quail eggs and finch eggs versus plasticine eggs varied as a function of egg size and shell thickness and strength. Overall, domestic finch eggs provided a better alternative to quail eggs because they were small enough to allow detection of predation events by small mammals and did not have an unnatural odor like plasticine. Potential problems with nest concealment, egg visibility, egg odors, and other factors must be resolved to enhance the design and reliability of artificial nest experiments.

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