scholarly journals Seasonal patterns in nest survival of a subtropical wading bird, the Hawaiian Stilt (Himantopus mexicanus knudseni)

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10399
Author(s):  
Kristen C. Harmon ◽  
Nathaniel H. Wehr ◽  
Melissa R. Price

Nest survival is influenced by where and when birds decide to breed. For ground-nesting species, nest-site characteristics, such as vegetation height and proximity to water, may impact the likelihood of nest flooding or depredation. Further, habitat characteristics, and thus nest survival, may fluctuate across the breeding season. The Hawaiian Stilt (‘Ae‘o; Himantopus mexicanus knudseni) is an endangered Hawaiian waterbird that nests in wetlands across the Hawaiian Islands. In this study, we used observational surveys and nest cameras to examine the impact of nest-site characteristics and day of nesting season on nest survival of the Hawaiian Stilt. Early nests had a higher chance of survival than late nests. For most of the nesting season, taller vegetation was correlated with increased nest survival, while shorter vegetation was correlated with increased nest survival late in the nesting season. Seasonal patterns in nest survival may be due to changes in parental behavior or predator activity. Nest depredation was responsible for 55% of confirmed nest failures and introduced mammals were the primary nest predators. Our study is the first to examine seasonality in nest survival of Hawaiian Stilts and suggests that, despite longer nesting seasons and year-round occupation of wetlands, late nesters in subtropical regions may have lower nest survival than early nesters, similar to trends observed in temperate regions.


Bird Study ◽  
2007 ◽  
Vol 54 (3) ◽  
pp. 307-314 ◽  
Author(s):  
John W. Mallord ◽  
Paul M. Dolman ◽  
Andy Brown ◽  
William J. Sutherland


PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9892
Author(s):  
Rocío Fernanda Jara ◽  
Ramiro Daniel Crego ◽  
Michael David Samuel ◽  
Ricardo Rozzi ◽  
Jaime Enrique Jiménez

Background Birds can maximize their reproductive success through careful selection of nest-sites. The ‘total-foliage’ hypothesis predicts that nests concealed in vegetation should have higher survival. We propose an additional hypothesis, the ‘predator proximity’ hypothesis, which states that nests placed farther from predators would have higher survival. We examined these hypotheses in the world’s southernmost forests of Navarino Island, in the Cape Horn Biosphere reserve, Chile (55°S). This island has been free of mammalian ground predators until recently, and forest passerines have been subject to depredation only by diurnal and nocturnal raptors. Methods During three breeding seasons (2014–2017), we monitored 104 nests for the five most abundant open-cup forest-dwelling passerines (Elaenia albiceps, Zonotrichia capensis, Phrygilus patagonicus, Turdus falcklandii, and Anairetes parulus). We identified nest predators using camera traps and assessed whether habitat characteristics affected nest-site selection and survival. Results Nest predation was the main cause of nest failure (71% of failed nests). Milvago chimango was the most common predator, depredating 13 (87%) of the 15 nests where we could identify a predator. By contrast, the recently introduced mammal Neovison vison, the only ground predator, depredated one nest (7%). Species selected nest-sites with more understory cover and taller understory, which according to the total-foliage hypothesis would provide more concealment against both avian and mammal predators. However, these variables negatively influenced nest survival. The apparent disconnect between selecting nest-sites to avoid predation and the actual risk of predation could be due to recent changes in the predator assemblage driven by an increased abundance of native M. chimango associated with urban development, and/or the introduction of exotic mammalian ground predators to this island. These predator assemblage changes could have resulted in an ecological trap. Further research will be needed to assess hypotheses that could explain this mismatch between nest-site selection and nest survival.



2012 ◽  
Vol 126 (1) ◽  
pp. 15
Author(s):  
Jon T. McRoberts ◽  
Nicole T. Quintana ◽  
W. Andrew Smith ◽  
Warren B. Ballard ◽  
F. Patrick Kehoe ◽  
...  

We studied Greater Scaup (Aythya marilla) nest site selection on Grassy Island, New Brunswick, during 1995 and 1996 by describing site selection in relation to habitat characteristics and association with larids using univariate comparisons. We pooled nesting data from both years and found that nesting sites were significantly closer to larid colonies and the edge of the patch of vegetation in which the nests were situated, had less forb canopy cover, more sedge cover, greater overhead concealment and lateral cover at 0–0.25 m, and less ground moisture than random sites. We evaluated Greater Scaup nests delimited as close to or far from larid colonies at 30 m and documented that nests closer to larid colonies were found in shorter vegetation that was closer to the edge of the patch of vegetation with less lateral cover at 0.25–0.5 m, but had greater overhead concealment than nests farther away. Advancements in the ecological understanding of the species, including habitat use patterns and species associations, will increase the likelihood of conservation successes.





2010 ◽  
Vol 88 (2) ◽  
pp. 214-218 ◽  
Author(s):  
Peter L.F. Fast ◽  
H. Grant Gilchrist ◽  
Robert G. Clark

Nest-site characteristics influence reproductive success in birds. Most studies of nest-site selection evaluate nest characteristics following the commencement of egg-laying, possibly overlooking the importance of pre-existing nest-site features that may be altered during the nesting process. Because Common Eiders ( Somateria mollissima (L.,1758)) often lay their eggs in nest bowls created in previous years, we were able to experimentally place moss or feather down in nest bowls prior to nesting. We then quantified whether these materials increased nest establishment or advanced laying dates relative to control nests and nests where material was removed prior to arrival of nesting females. We found no difference in the likelihood of successful nest establishment between groups. However, the onset of incubation occurred 2–3 days earlier in nest bowls that contained feather down versus nest bowls with little or no nesting material. Nest bowls containing feathers or vegetation may be selected first if they increase nest survival, perhaps by enhancing egg concealment during the critical early-laying period. The presence of material for egg concealment may be particularly important in nesting environments where tall or dense vegetation is not available to provide nest cover.



The Condor ◽  
2021 ◽  
Vol 123 (1) ◽  
Author(s):  
Paige A Byerly ◽  
Susan Zaluski ◽  
Daniel Nellis ◽  
Paul L Leberg

Abstract Determining how site characteristics influence reproductive success can help guide conservation planning for declining wildlife populations. For colonially breeding seabirds, nest survival and predation risk can be influenced by both colony and nest site characteristics such as colony size, nest density, and nest location. We evaluated the reproductive success of a declining population of Roseate Terns (Sterna dougallii) in the United States and British Virgin Islands to identify primary causes of nest failure and investigate the influence of colony and nest site covariates on nest survival. In addition, we measured the influence of colony characteristics on chick provisioning to determine if resource competition in larger colonies affected foraging rates. Monitoring was conducted in 2017–2018 via motion-triggered cameras, which enable 24-hr monitoring with minimal nest disturbance. Nest survival was defined by both hatch success and early chick success, defined as a chick surviving from hatching through the fourth post-hatch day. We monitored 118 nests in 6 colonies over the 2 breeding seasons. We found that predation was the primary cause of nest failure. Both hatch and nest success increased with colony size, and neither nest survival nor predation probability was influenced by individual nest site characteristics. Provisioning rates were comparable among colony sites and did not vary with colony size. Our results suggest that directing management efforts toward enhancing colony size, rather than focusing on nest site characteristics, can be beneficial for tropical seabird conservation.



2019 ◽  
Vol 66 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Jin-Ming Zhao ◽  
Chen Yang ◽  
Ying-Qiang Lou ◽  
Mei Shi ◽  
Yun Fang ◽  
...  

Abstract Nest survival is a vital component of breeding success, and affects population dynamics, as the loss of nests is the main cause of reproductive failure in birds. To identify key factors for the conservation of Chinese grouse Tetrastes sewerzowi, we tested the effects of nest concealment, nest age, nesting season, and habitat edge on nest daily survival rate (DSR) of Chinese grouse using 54 nests found at Lianhuashan Nature Reserve, Gansu, China, 2009–2012. Moreover, we controlled for the effect of research activity by testing the effect of nest checks on DSR. Overall, mammal predation caused 93% of nest failures. DSR was 0.986 ± 0.0038 in the constant model and the probability of a nest with a full clutch of 6 eggs surviving the entire 40-day nesting period was 0.526 ± 0.090. DSR decreased with nest age and nesting season (from 19 May to 3 July). Mammals instead of avian predators being responsible for most nest failures suggest that nest sites might be selected to avoid visual avian predators, but not olfactory mammalian predators, and the decreasing trend of DSR with nest age and nesting season could attribute to an additive exposure effect. Moreover, nest checks conducted by investigators significantly lowered nest DSR, especially during the late period of nesting season and for older nests. Mammalian predators might locate the nest site by following the investigator’s odor. Based on our results, we suggest that the late incubation stage is a particularly vulnerable period for nest survival of Chinese grouse and those researchers should adjust their activities around nests to balance the need of acquiring accurate data and decreasing nest predation risk.



The Condor ◽  
2013 ◽  
Vol 115 (1) ◽  
pp. 155-162 ◽  
Author(s):  
Theresa L. Pope ◽  
Tara J. Conkling ◽  
Kathryn N. Smith ◽  
Melanie R. Colón ◽  
Michael L. Morrison ◽  
...  




2006 ◽  
Vol 120 (3) ◽  
pp. 342
Author(s):  
Serge Larivière ◽  
Lyle R. Walton ◽  
François Messier

Striped Skunks (Mephitis mephitis) are important predators of duck eggs in the Canadian prairies. We estimated the impact of individual Striped Skunks on duck nests by intensive observations of foraging movements and depredation of duck nests in southern Saskatchewan, 1993-1994. Nightly, skunk movements were variable (range 0-20 km per night), and did not differ among seasons for females, or between males and females during the parturition/rearing season. Overall, nightly movement of Striped Skunks averaged 7.4 km for females (SD = 5.9 km, n = 20 females) and 6.7 km for males (SD = 3.2 km, n = 5 males). During 1,873 h of radio-tracking, we observed depredation of 10 duck nests by 8 skunks (7 F, 1 M). Using our observed estimate of one depredation for every 187 h, and averaged nightly activity of 8-10 h per night, we estimated that individual skunks find one duck nest every 19-23 nights. Thus, during the 60-day nesting season for ducks (mid-May to mid-July), individual skunks probably find 2-3 duck nests. These observations reinforce the growing evidence that, at normal duck nest densities (<2.5 nests/ha), depredation of eggs by Striped Skunks is opportunistic, and the impact of Striped Skunks on duck nests is a direct function of Striped Skunk abundance.



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