Movements and Survival of Lark Bunting Fledglings

Abstract

We quantified post-fledging pre-independence behavior and survival in Lark Buntings (Calamospiza melanocorys) using radio-telemetry. Brood division was recorded in six broods and was maintained throughout the observed fledgling care period. Chicks were capable of short flights (up to 25 m) by fledgling day 6 and longer flights (to 100 m) by fledgling day 13. During the first three weeks after fledging, juveniles moved as far as 800 m from nests. Nine of 23 (39%) monitored fledglings died within 15 days of fledging, primarily due to predation by raptors. Daily survival rates were 0.953 ± 0.019 for fledgling days 0–9, 0.955 ± 0.038 for fledgling days 10–20, and 0.953 ± 0.015 for fledgling days 0–20. The probability of surviving fledgling days 0–20 was 0.367. More quantification of juvenile survival is clearly needed to understand the role of post-fledging mortality in source-sink dynamics. Los Movimientos y Supervivencia de los Volantones de Calamospiza melanocorys Resumen. Cuantificamos la conducta y la supervivencia de volantones de Calamospiza melanocorys antes de independizarse de sus padres usando telemetría de radio. La división de la nidada se registró en seis nidadas y se mantuvo a través del período del cuidado de los volantones. Tras seis días de haber abandonado el nido, los polluelos eran capaces de realizar vuelos cortos (de hasta 25 m) y para el día trece ya realizaban vuelos más largos (a 100 m). Durante las primeras tres semanas después de salir del nido, los juveniles se movieron hasta 800 m de los nidos. Nueve de 23 (39%) volantones se murieron en los primeros 15 días fuera del nido, principalmente debido a depredación por aves rapaces. Las tasas diarias de supervivencia fueron de 0.953 ± 0.019 para los días 0 a 9, 0.955 ± 0.038 para los días 10 a 20, y 0.954 ± 0.015 para días 0 a 20. La probabilidad de sobrevivir entre los días 0 y 20 fue de 0.367. Se necesita más cuantificacion de la sobrevivencia en la etapa juvenil para entender el papel de la mortalidad tras la salida del nido en la dinámica de fuente-sumideros.

Survival Rates of Young MagpiesPica picain a Mountain Population of Eastern Spain

“…Numerous studies deal with bird breeding success until nestlings have left the nest (e.g., Nice 1957, De La Puente & Yanes 1995, Gil-Delgado & Lacort 1996, Ponz et al 1996, Yanes & Suárez 1996. However, studies covering the period between fledgling and the next breeding season are scarce (e.g., Husby & Slagsvold 1992, Anders et al 1997, Adams et al 2001, Naef-Daenzer et al 2001, Todd et al 2003, Adams et al 2006, Wiens et al 2006). It has been suggested that in this period there are two moments when mortality may be most important.…”

Survival of grasshopper sparrows (Ammodramus savannarum) during two important life stages in grassland managed with fire and grazing

“…Young fledglings are unable to thermoregulate for long periods (Yackel Adams et al 2006). Therefore, we hypothesized that cool, wet nights would decrease daily survival rates, as would extreme heat.…”

“…For examining chick condition we used culmen length, wing chord, tarsus length, and mass measurements that were taken at the time of transmitter attachment. We also created a rank of body condition by dividing the mass of the chick with the transmitter attached by the greatest mass of any chick in the clutch (Yackel Adams et al 2006). Body condition, whether by rank or using mass alone, has been related to fledgling survival in previous studies (Krementz et al 1989, Yackel Adams et al 2006, Suedkamp Wells 2007.…”

“…We also created a rank of body condition by dividing the mass of the chick with the transmitter attached by the greatest mass of any chick in the clutch (Yackel Adams et al 2006). Body condition, whether by rank or using mass alone, has been related to fledgling survival in previous studies (Krementz et al 1989, Yackel Adams et al 2006, Suedkamp Wells 2007. 4) Finally, we added the effect of treatment and nine habitat measurements taken from the microhabitat to the best model from step three.…”

“…The stage after nestlings fledge, or the postfledging period, is of critical importance for grassland birds because fledglings generally experience extremely high mortality rates (Anders 1998, Lang et al 2002, Berkeley et al 2007. During this period, fledglings remain dependent on parental care while they learn to fly, feed on their own, and hide from predators , Yackel Adams et al 2006. Despite fledgling vulnerability at this time and the potential importance of the postfledging life stage in the decline of grassland birds, few studies have focused on it (Berkeley et al 2006).…”