Survival of translocated Columbian Sharp-tailed Grouse: recognizing trends in post-release mortality to improve reintroductions

Abstract

Survival of translocated prairie-grouse (Tympanuchus spp.) is often low in the first few weeks or months following release into a novel environment. Understanding the processes and mechanisms that influence short-term, post-release survival, such as Allee effects (i.e., inverse density dependence), or individual characteristics of translocated individuals (e.g., age, sex) is imperative for designing successful translocation programs. Additionally, identifying timeframes during which translocated individuals are particularly vulnerable to mortality is especially useful for population management. We translocated 215 Columbian Sharp-tailed Grouse (T. phasianellus columbianus; CSTG) as a species reintroduction project to historical habitat in northeastern Nevada from 2013 to 2017 and quantified annual post-release survival probabilities during the 150-d breeding season. In a Bayesian framework, we first identified a prospective 40-d threshold in which the daily probability of survival substantially increased from before to after the threshold. Next, while accounting for the threshold effect at 40 d, we identified an age by population size interaction in which survival of yearling and adult CSTG changed across time. Yearlings exhibited substantially higher survival probabilities when the population at the release site was small (≤ 10 males on lek) during early translocation years, and adults exhibited substantially higher survival probabilities when the population at the release site was moderate or large (≥ 8 males on lek) during latter years of the translocation. This might represent inverse density dependent effects on survival wherein adult survival improved concomitantly with increases in population sizes. Shortterm, post-release survival is less intuitive for yearlings, but yearlings greatly outperformed adults during the critical first three years of the reintroduction (i.e., the establishment phase) when the population at the release site was very small. In future reintroduction projects, establishing a population with translocated yearling CSTG followed by adults might hasten conservation goals. Survie de Tétras à queue fine colombiens ayant été transférés : reconnaître la tendance des mortalités post-lâcher pour améliorer la réintroductionRÉSUMÉ. La survie de tétras des prairies (Tympanuchus spp.) ayant été transférés est souvent faible au cours des premières semaines ou des premiers mois suivant leur lâcher dans un nouvel environnement. Il faut comprendre les processus et les mécanismes qui influent sur la survie à court terme après un lâcher, comme les effets Allee (c.-à-d. la dépendance inverse à la densité) ou les caractéristiques individuelles des individus transférés (p. ex. l'âge, le sexe), pour concevoir des programmes de transfert qui auront du succès. De plus, la détermination des périodes pendant lesquelles les individus transférés sont particulièrement vulnérables à la mortalité est particulièrement utile pour ceux qui gèrent les populations. Dans le cadre d'un projet de réintroduction de l'espèc...

Lesser prairie‐chicken dispersal after translocation: Implications for restoration and population connectivity

“…Of all released birds, 13.1% died (n = 54) and 9.7% went missing (n = 40) within the first 2 weeks after release, indicating potentially substantial mortality associated with the act of translocation, adjustment to the new environment, and dispersal movement after translocation (Teige et al, 2023). High initial mortality rates are not unprecedented among prairie grouse translocations; Mathews et al (2022) found similar rates of mortality (0.992 daily survival) within the first 40 days after Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus) translocation.…”

“…High initial mortality rates are not unprecedented among prairie grouse translocations; Mathews et al. ( 2022 ) found similar rates of mortality (0.992 daily survival) within the first 40 days after Columbian sharp‐tailed grouse ( Tympanuchus phasianellus columbianus ) translocation.…”

Assessment of lesser prairie‐chicken translocation through survival and lek surveys

“…Spring translocated Gunnison sage‐grouse had lower survival during the first 75 days following release than during the remainder of the first year (Apa et al 2022). Similarly, translocated Columbian sharp‐tail grouse had a survival rate of 42% for adults and 67% for yearlings during the breeding season, with substantially greater mortality for the 40‐50 days after release (Mathews et al 2016, 2022). Within the breeding season, we found adult survival was lowest the third week of April, and was lower than survival estimates for females during that week in nontranslocated birds (~0.92; Plumb 2015).…”

Evaluating satellite‐transmitter backpack‐harness effects on greater sage‐grouse survival and device retention in the Great Basin

“…Radio and satellite telemetry are widely used to study movement and demographics of gallinaceous birds including greater sage‐grouse ( Centrocercus urophasianus ; Gibson et al 2013, Severson et al 2019, Olsen et al 2021a, Mathews et al 2022, Schuyler et al 2022). Sage‐grouse have experienced pronounced range contractions and population declines, have twice been petitioned for listing under the Endangered Species Act (U.S.…”