Mayfield estimates versus apparent nest success in colonial geese

Abstract

Unbiased estimates of nest survival are often required to make robust inference about population and habitat management. We studied nest survival of lesser snow (Anser caerulescens caerulescens) and Ross's (A. rossii) geese at Karrak Lake, Nunavut, in Canada's central Arctic, 1995Arctic, -2012. We monitored nests throughout the nesting period, from early egg-laying to late incubation, and revisited nests after predicted hatch dates to determine nest fate. Despite high nesting density and high nest visibility, detection of failed nests was lower than active nests; consequently, Mayfield nest success estimated with Program MARK was always lower than apparent nest success, the latter defined as the proportion of detected nests that produced !1 offspring. From data that included nests found after failure, however, annual nest survival estimated by Program MARK was related (r 2 ¼ 0.98 for both species) to apparent estimates, permitting accurate estimation of true nest success from apparent estimates. Nest survival probability (i.e., nest survival) in both species modeled with Program MARK varied annually (lesser snow geese ¼ 0.234-0.795, Ross's geese ¼ 0.273-0.901) and daily nest survival declined with nest age in most years. Within years, nests initiated later experienced lower survival for both lesser snow and Ross's geese (nest initiation date (NID), b NID ¼ À0.068 [95% CI ¼ À0.096, À0.041] and À0.082 [À0.119, À0.046], respectively). Nest survival was higher when days were relatively warm and dry for lesser snow geese (b daily weather ¼ 0.089 [0.054, 0.402]), but weather did not influence nest survival of Ross's geese. Disturbance by researchers had no influence on nest survival of either species. Sampling for contemporary estimators of nest survival that account for differential detection probabilities between active and inactive nests to produce unbiased estimates may not always be logistically feasible; thus, we urge researchers at least to derive predictive equations from a subset of nests specific to study sites and species to correct apparent estimates. Ó 2019 The Wildlife Society. KEY WORDS apparent nest success, arctic, lesser snow geese, Mayfield nest success, nest initiation date, nest survival, Ross's geese.

Local population collapse of Ross's and lesser snow geese driven by failing recruitment and diminished philopatry

“…Increased emigration probability was linked to low nest success in both species (Wilson et al 2016), as been found in other colonial‐breeding birds such as Audouin's gulls Larus audouinii (Cam et al 2004) and lesser kestrels Falco naumanni (Serrano et al 2001). Ross's geese consistently had higher nest success (Traylor 2010, Kellett and Alisauskas 2019) and thus consistently lower emigration probability than snow geese (Wilson et al 2016). Such negative linkages of emigration probability to nesting success are consistent with adaptive behavioral response whereby individuals that have been unsuccessful in reproduction (or even skipped breeding and deferred an attempt to a subsequent year) disperse to habitats with improved chances of successful reproduction (Wilson et al 2016).…”

Misinformation tactics protect rare birds from problem predators

“…This effect size benchmarks well against the doubling of prey responses to the removal of invasive predators using traditional lethal techniques when they are effective (32). Protecting nests laid in the first third of the nesting season provides a disproportionately greater fitness value because their survival is naturally higher than for nests laid later (33)(34)(35).…”

“…Nests were revisited every 2 to 4 days to check their status, service the camera, and download video footage. Deploying cameras at nests was considered necessary to accurately determine nest fates and the identity of predators, and any effect of the cameras or observers at nests on the fate of nests was assumed to be constant across sites and years (33,44). Nest fates were determined either by direct observation of the hatch/failure event from the cameras (for the majority of nests) (see movie S1), by observing newly hatched chicks in the nest (for a minority of successful nests), or by eliminating the possibility of a hatch event by counting forward from known laying dates (for a minority of failed nests).…”

Nest traits and major flooding events influence nest survival of Emperor Geese while regional environmental variation linked to climate does not

“…Researchers displacing females from nests can expose the nest to predators, which may bias estimates of DSP and nest survival if not mitigated or addressed in analyses (Rotella et al 2000). Reduced DSP following observer visits (Iles et al 2013, Rizzolo et al 2014, Meixell and Flint 2017) and nest-trapping events (Uher-Koch et al 2015) have been documented in some water bird studies, although other studies report no effects (e.g., Sedinger 1990, Kellett andAlisauskas 2019). We found evidence that visiting nests marginally decreased DSP and subsequently nest survival.…”