Age and wing development at fledging balances mortality in and out of the nest in a compromise between parents and offspring.

Aim Adult survival is central to theories explaining latitudinal gradients in life history strategies. Life history theory predicts higher adult survival in tropical than north temperate regions given lower fecundity and parental effort. Early studies were consistent with this prediction, but standard‐effort netting studies in recent decades suggested that apparent survival rates in temperate and tropical regions strongly overlap. Such results do not fit with life history theory. Targeted marking and resighting of breeding adults yielded higher survival estimates in the tropics, but this approach is thought to overestimate survival because it does not sample social and age classes with lower survival. We compared the effect of field methods on tropical survival estimates and their relationships with life history traits. Location Sabah, Malaysian Borneo. Time period 2008–2016. Major taxon Passeriformes. Methods We used standard‐effort netting and resighted individuals of all social and age classes of 18 tropical songbird species over 8 years. We compared apparent survival estimates between these two field methods with differing analytical approaches. Results Estimated detection and apparent survival probabilities from standard‐effort netting were similar to those from other tropical studies that used standard‐effort netting. Resighting data verified that a high proportion of individuals that were never recaptured in standard‐effort netting remained in the study area, and many were observed breeding. Across all analytical approaches, addition of resighting yielded substantially higher survival estimates than did standard‐effort netting alone. These apparent survival estimates were higher than for temperate zone species, consistent with latitudinal differences in life histories. Moreover, apparent survival estimates from addition of resighting, but not from standard‐effort netting alone, were correlated with parental effort as measured by egg temperature across species. Main conclusions Inclusion of resighting showed that standard‐effort netting alone can negatively bias apparent survival estimates and obscure life history relationships across latitudes and among tropical species.

Increasing elk (Cervus elaphus nelsoni) populations across the West in response to increased demand for recreational and hunting opportunities may have negative, unintended consequences for disease transmission risk. Historically, free-ranging elk populations were not thought to sustain brucellosis (Brucella abortus), but recent studies suggest increasing elk densities may result in free-ranging elk serving as maintenance hosts for the disease. We evaluated spatial variation in elk density, group sizes, and adult female brucellosis seroprevalence in 39 elk management districts in the Greater Yellowstone Ecosystem using a Bayesian approach. We used modeled relationships to estimate the effects of reducing elk density by 10-90% on grouping patterns and seroprevalence rates. Reducing the density of the 3 highest density elk herds by 10%, 50%, and 90% was predicted to result in a 9%, 39%, and 59% decrease in mean group size, whereas reducing the density of the 3 lowest density elk herds was predicted to result in only a 0%, 0.7%, and 1.3% decrease in mean group size. We estimated seroprevalence rates of 0.01-0.27 across management districts, and seroprevalence increased as elk density increased. For the 7 of 39 management districts with >10% estimated seroprevalence, 10%, 50%, and 90% reductions in elk density resulted in predicted mean seroprevalence reductions of 2%, 7%, and 9%, respectively. For the 14 management districts with 1% estimated seroprevalence, 10%, 50%, and 90% reductions in elk density resulted in no measurable change in predicted mean seroprevalence. Our results suggest that elk density has an important effect on elk group sizes, which may influence the risk of brucellosis transmission and resultant exposure rates. Manipulating elk density may in turn affect brucellosis seroprevalence rates. However, debate among the diverse stakeholders involved in elk management on the effectiveness of reducing density, group sizes, and brucellosis exposure rates in elk, relative to other interests and objectives, is necessary prior to manipulation of elk density for this purpose. Ó 2015 The Wildlife Society.

We compared 4 external radiotransmitter attachment techniques to determine the optimum attachment method on chicks of 2 galliform species. The attachment methods included tissue glue, silicone gel, suturing, and leg harness. The study was conducted in captivity with a 2-phase assessment: first with northern bobwhite (Colinus virginianus), and then chukar (Alectoris chukar) chicks. We applied each technique and assessed effects on growth rates, retention times, ease of attaching the transmitter, and effects on physical development. No apparent adverse impacts on chicks were observed for any of the attachment techniques. We found the leg-harness technique was most reliable in terms of retention time, required the least amount of handling time, and was the simplest to administer. Modifications to our suture technique likely would result in similar retention times, but would still require additional handling time and complexity in attaching transmitters. ß 2011 The Wildlife Society.

ABSTRACT. Skewed sex ratios can have negative implications for population growth if they do not match a species' life history. A skewed tertiary sex ratio has been detected in a population of Mountain Plover (Charadrius montanus), a grassland shorebird experiencing population declines. To study the cause of the observed male skew, we examined three early life stages between egg and fledgling in eastern Colorado from 2010 to 2012. This allows us to distinguish between egg production and chick survival as an explanation for the observed skew. We examined the primary sex ratio in eggs produced and the secondary sex ratio in hatched chicks to see if the sex ratio bias occurs before hatching. We also determined the sex ratio at fledging to reveal sex-specific mortality of nestlings. The primary sex ratio was 1.01 (± 0.01) males per female. The secondary sex ratio consisted of 1.10 (± 0.02) males per female. The probability of a chick surviving to fledging differed between males (0.55 ± 0.13) and females (0.47 ± 0.15), but the precision of these survival estimates was low. Sex ratios in early life stages of the Mountain Plover do not explain the skewed sex ratio observed in adults in this breeding population. Sex-ratios de la production d'oeufs à l'envol chez le Pluvier montagnardRÉSUMÉ. Des sex-ratios déséquilibrées peuvent avoir des effets négatifs sur la croissance d'une population si elles sont trop éloignées de la biodémographie naturelle de l'espèce. Une sex-ratio tertiaire déséquilibrée a été détectée chez une population de Pluvier montagnard (Charadrius montanus), un oiseau de rivage qui se reproduit dans les prairies et dont les populations sont en baisse. Dans le but d'étudier la cause du déséquilibre observé favorisant les mâles, nous avons examiné trois stades précoces des oeufs à l'envol, dans l'est du Colorado de 2010 à 2012. Cet examen nous a permis d'établir si la production d'oeufs ou la survie des jeunes pouvait expliquer la sex-ratio déséquilibrée. Nous avons examiné la sex-ratio primaire des oeufs et la sex-ratio secondaire des poussins éclos afin de déterminer si le déséquilibre de la sex-ratio était présent avant l'éclosion. Nous avons aussi déterminé la sex-ratio des jeunes à l'envol pour obtenir la mortalité spécifique au sexe des oisillons. La sex-ratio primaire s'élevait à 1,01 (± 0,01) mâle par femelle. La sex-ratio secondaire était de 1,10 (± 0,02) mâle par femelle. La probabilité qu'un oisillon survive jusqu'à l'envol était différente entre les mâles (0,55 ± 0,13) et les femelles (0,47 ± 0,15), mais la précision de ces estimations de survie était faible. La sex-ratio observée aux stades précoces n'explique pas le déséquilibre de la sex-ratio chez les adultes de cette population nicheuse de Pluvier montagnard.