Differences in Susceptibility to Predation during Nesting Between Pied and Black Stilts (Himantopus spp.)

The Auk ◽  
1986 ◽  
Vol 103 (2) ◽  
pp. 273-280 ◽  
Author(s):  
Raymond J. Pierce
Keyword(s):  
New Zealand ◽  
Breeding Success ◽  
Site Fidelity ◽  
Indirect Evidence ◽  
Nesting Success ◽  
Nest Failure ◽  
Foraging Patterns ◽  
High Site ◽  
Breeding Seasons ◽  
The Impact

Abstract The nesting success of the Pied Stilt (Himantopus himantopus leucocephalus) and the endangered Black Stilt (H. novaezealandiae) was studied for three consecutive breeding seasons (1977-1979) in New Zealand. Black Stilts had a breeding success of less than 1%, compared with over 8% for Pied Stilts. Predation by feral mammals was the main cause of nest failure for both species, but the impact was greater on Black Stilts. Direct and indirect evidence (including trapping predators) suggests that these introduced ground predators kill many chicks. Several factors made Black Stilts vulnerable, particularly their nesting along stream banks that were often frequented by predators; Pied Stilts nested in swamps where predators were few. Black Stilt chicks took up to 2 weeks longer to fledge and their foraging patterns made them more vulnerable than Pied Stilt chicks. Other factors that possibly increased predation risk of Black Stilts include nesting at times of high predator activity, solitary nesting, high site fidelity, ineffective distraction displays, and lack of a disruptive camouflage pattern in adults. Introduced ground predators probably have contributed greatly to the decline of Black Stilts. Pied Stilts have not been affected similarly, because their evolutionary past has included long exposure to ground predators.

Effects of habitat and introduced mammalian predators on the breeding success of Yellow-eyed Penguins Megadyptes antipodes, South Island, New Zealand

1999 ◽  
Vol 5 (1) ◽  
pp. 16 ◽  
Author(s):  
Hiltrun Ratz ◽  
Brian Murphy
Keyword(s):  
New Zealand ◽  
Breeding Success ◽  
East Coast ◽  
Marked Effect ◽  
Forest Edge ◽  
Introduced Predators ◽  
Mammalian Predators ◽  
Predator Abundance ◽  
Breeding Seasons ◽  
Predator Guild

The endemic Yellow-eyed Penguin Megadyptes antipodes is threatened by habitat loss and introduced predators on mainland New Zealand. Nine colonies in the Catlins (south-east coast of South Island) were studied to measure breeding success, penguin abundance, and predator abundance in three successive breeding seasons (1991/92 to 1993/94). Nest numbers increased in all nine colonies in the three years despite predation (probably by Stoats Mustefa erminea) being the most important cause of breeding failure. Larger colonies with higher breeding success were in small gullies with limited shrubs and bushes rather than in the most intact mature forest colonies hitherto assumed to be optimal habitat for the birds. Penguin nests were concentrated near the forest edge, but predators were not, so the predation risk was not elevated near the forest edge. Fragmentation of the original forest habitat had no observable adverse effect on breeding success. Stoats dominated the predator guild, while Ferrets M. furo and Feral Cats Felis catus were rare. Trapping to kill predators early in the season had no marked effect on subsequent predation losses, but trapping intervention when a predation outbreak occurred curtailed further chick deaths. A simple population model predicts that Yellow-eyed Penguins populations will grow provided the average total chicks loss is less than 43% per season, or at least 0.85 chick per nest fledges each year. This requires predation losses to be less than 34%.

Reproduction of Pied Flycatchers (Ficedula hypoleuca) in Good and Bad Breeding Seasons in a Northern Marginal Area

The Auk ◽  
1984 ◽  
Vol 101 (3) ◽  
pp. 439-450 ◽  
Author(s):  
Antero Järvinen ◽  
Risto A. Väisänen
Keyword(s):  
Breeding Success ◽  
Egg Size ◽  
Local Population ◽  
Ficedula Hypoleuca ◽  
Nesting Success ◽  
Egg Laying ◽  
Female Size ◽  
Finnish Lapland ◽  
Breeding Seasons ◽  
Better Than

Abstract We studied relationships between female size, date of egg laying, clutch size, egg size, and breeding success in Pied Flycatchers (Ficedula hypoleuca) in a marginal area in northwestern Finnish Lapland (69°N). Average June temperatures in 1975-1981 were used to classify years into "good" (warm) and "bad" (cold) breeding seasons. In general, early and warm springs were followed by "good" breeding seasons: females were heavier, laying was earlier, clutches were larger and contained larger eggs, and hatching and fledging success were better than in late and cold springs. Mainly due to low nesting success in "bad" breeding seasons, the local population could not maintain itself; immigration from the south was needed. We suggest that spring weather may provide information concerning the character of the coming breeding season, which may help birds to maximize their lifetime production of young.

Predation at Sooty Shearwater Puffinus griseus colonies on the New Zealand mainland: is there safety in numbers?

1999 ◽  
Vol 5 (4) ◽  
pp. 347 ◽  
Keyword(s):  
New Zealand ◽  
Conceptual Model ◽  
Breeding Success ◽  
Rattus Norvegicus ◽  
Breeding Birds ◽  
Breeding Failure ◽  
Safety In Numbers ◽  
Breeding Seasons ◽  
Norway Rats ◽  
Extinction Vortex

Burrow occupancy, survivorship, and breeding success were assessed at eight Sooty Shearwater Puffinus griseus colonies along the southeastern coast of New Zealand during the 1994/95 and 1995/96 breeding seasons. An average 46% and 47% of burrows contained breeding birds, but only three colonies had chicks survive to fledge. Most breeding failures were at the egg and early-chick phase. A large proportion of adults were killed at some places, causing the extinction of two of our study colonies. Predation by Stoats Mustefa erminea was the main cause of breeding failure and adult loss at most mainland colonies, but Norway Rats Rattus norvegicus were the principal predator at one colony. Protection of adults, eggs and young chicks from predators is crucial if mainland colonies are to persist. A conceptual model predicts that predation becomes part of the extinction vortex as the size of a colony dwindles because the depredations of a few rogue predators have catastrophic impacts on the few remaining birds.

scholarly journals Reproductive success of the threatened Reed Parrotbill Paradoxornis heudei in non-harvested and harvested reedbeds in the Yangtze River estuary, China

2011 ◽  
Vol 22 (3) ◽  
pp. 339-347 ◽  
Author(s):  
ANTHONY BOULORD ◽  
ZHANG MEI ◽  
WANG TIAN-HOU ◽  
WANG XIAO-MING ◽  
FRÉDÉRIC JIGUET
Keyword(s):  
Breeding Season ◽  
River Estuary ◽  
Weather Conditions ◽  
Nesting Success ◽  
Conservation Strategies ◽  
Yangtze River Estuary ◽  
Nest Failure ◽  
Adverse Weather ◽  
Daily Nest Survival ◽  
The Impact

SummaryUnderstanding the factors that affect the nesting success of threatened birds is essential in designing effective conservation strategies. Here we compare nesting success of the Reed Parrotbill Paradoxornis heudei in annually harvested and non-harvested reedbed habitats in the Chongming Dongtan Nature Reserve in China, by recording the number of nestlings produced per nest and the causes of nest failure. We modelled daily nest survival rate (DSR) by considering the effects of harvesting, vegetation characteristics, year, date, advancement within the breeding season, nest age and nearest-nest distance, using the program MARK. Nest densities, but not the number of fledglings per nest, were significantly lower in harvested than non-harvested reedbed habitats. The best-fit DSR model estimated constant survival; none of the tested co-variables had significant effects. Moreover, harvesting did not affect the date of breeding initiation, likelihood of nest failure, or causes of nest failure, as vegetation cover was not significantly different between harvested and non-harvested reedbeds during the whole breeding season. Nest failure following adverse weather conditions was unusually common in harvested and non-harvested reedbeds, accounting for as many nest failures as depredation. However, comparisons with other studies suggest that deriving a conclusion on the impact of harvesting on nesting success is not straightforward and is probably linked to environmental characteristics affecting reed growth.

Efficacy of Crisis Intervention

Crisis ◽  
1999 ◽  
Vol 20 (2) ◽  
pp. 78-85 ◽  
Author(s):  
Thomas Reisch ◽  
Petra Schlatter ◽  
Wolfgang Tschacher
Keyword(s):  
Crisis Intervention ◽  
Intervention Program ◽  
Suicide Ideation ◽  
Indirect Evidence ◽  
Well Being ◽  
Term Therapy ◽  
Contributing Factors ◽  
Step Therapy ◽  
Long Term Therapy ◽  
The Impact

This study assesses the efficacy of the treatment approach implemented in the Bern Crisis Intervention Program, where particular emphasis is placed on the remediation of suicide ideation and suicidal behavior, and depression, fear, and phobia are generally considered to be contributing factors. Four questionnaires addressing psychopathology, emotional well-being, social anxiety, and personality were administered prior to and after the treatment of 51 patients over a period of 2 to 3 weeks. The reduction of symptoms contributing to suicidal ideation and behavior was interpreted as indirect evidence of an antisuicidal effect of the program. Significant improvements were found in the psychopathology ratings, with depression and anxiety showing the largest reductions. The impact on personality and social phobia, however, was only moderate, and on average patients still exhibited symptoms after attending the program. This residual symptomatology points to the necessity of introducing a two-step therapy approach of intensive intervention targeted at the precipitating causes of the crisis, augmented by long-term therapy to treat underlying problems.

scholarly journals A multiscale assessment of Red-tailed Hawk reproductive success relative to urban density and habitat type

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Justin H White ◽  
Jessi L Brown ◽  
Zachary E Ormsby
Keyword(s):  
Urban Areas ◽  
Urban Expansion ◽  
Habitat Type ◽  
Nesting Success ◽  
Arid Environments ◽  
Hatch Date ◽  
Urban Density ◽  
Landscape Characteristics ◽  
Suburban Areas ◽  
Breeding Seasons

Abstract Despite the unique threats to wildlife in urban areas, many raptors have established successfully reproducing urban populations. To identify variations in raptor breeding ecology within an urban area, we compared metrics of Red-tailed Hawk reproductive attempts to landscape characteristics in Reno and Sparks, NV, USA during the 2015 and 2016 breeding seasons. We used the Apparent Nesting Success and logistic exposure methods to measure nesting success of the Red-tailed Hawks. We used generalized linear models to relate nesting success and fledge rate to habitat type, productivity to hatch date (Julian day) and hatch date to urban density. Nesting success was 86% and 83% for the respective years. Nesting success increased in grassland-agricultural and shrub habitats and decreased in riparian habitat within the urban landscape. Productivity was 2.23 and 2.03 per nest for the breeding seasons. Fledge rates were 72% and 77%, respectively, and decreased in riparian areas. Nestlings hatched earlier with increased urban density and earliest in suburban areas, following a negative quadratic curve. Nesting success and productivity for this population were high relative to others in North America. Productivity increased in habitats where ground prey was more accessible. We suggest that suburban areas, if not frequently disturbed, provide sufficient resources to sustain Red-tailed Hawks over extended periods. As urban expansion continues in arid environments globally, we stress that researchers monitor reproductive output across the urban predator guild to elucidate patterns in population dynamics and adaptation.

scholarly journals Green morays (Gymnothorax funebris) have sedentary ways in mangrove bays, but also ontogenetic forays to reef enclaves

2021 ◽  
Author(s):  
Matthew S. Kendall ◽  
Laughlin Siceloff ◽  
Ashley Ruffo ◽  
Arliss Winship ◽  
Mark E. Monaco
Keyword(s):  
Home Range ◽  
Site Fidelity ◽  
Home Range Size ◽  
Range Size ◽  
Caribbean Region ◽  
History Of ◽  
High Site ◽  
Single Night ◽  
Exploratory Movements ◽  
Moray Eel

AbstractSurprisingly, little is known about basic life history of the largest moray eel species in the Caribbean region, the green moray eel (Gymnothorax funebris). Sixteen eels were captured from the mangrove fringe in multiple bays on St. Croix, USVI, implanted with coded acoustic transmitters, and their movements were tracked for up to 11 months using an array of 37 stationary acoustic receivers. They exhibited high site fidelity in the bays during their residence, using the same general parts of individual bays and did not switch bays except for one individual. There was no relationship between eel size (mean TL = 83 cm, range = 54–126 cm) and home range size (mean area of 95% KUD = 5.8 ha ± 0.7 SE). Most individuals were more frequently detected at night than during the day suggesting greater nocturnal activity. Several of the larger eels (mean TL = 93 cm ± 5.9 SE) showed clear and permanent emigration tracks out of the mangrove estuary to coral reef habitats offshore. For some individuals, these habitat shifts were preceded by exploratory movements away from the eel’s typical home range the night before emigration. All final emigration events took place nocturnally, happened during a single night, and occurred during months from December to May. Mean emigration speed was 3.4 km/h. This study is the first documentation of an ontogenetic habitat shift in moray eels, as well as the first determination of home range size for this species and their site fidelity in mangrove habitats.

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