Breeding Dispersal and Philopatry in the Tree Swallow

Abstract

To study the patterns and determinants of philopatry and breeding dispersal in the Tree Swallow (Tachycineta bicolor) we analyzed the records of 356 males and 1459 females captured in more than one breeding year around Ithaca, New York. Of these captures, only 4% of male and 14% of female breeders dispersed to a new site for breeding. With our combination of intensive study areas in Tompkins County, New York, and the efforts of volunteer banders throughout New York and surrounding states, we could have detected dispersal in excess of 400 km from the initial breeding site. Randomization tests revealed, however, that breeders dispersed much shorter distances than they could have been detected. Detailed analyses of recaptures in Tompkins County showed that over a 22-km range of distances, the chances of dispersal to a new breeding site declined with the distance from the original breeding site. Females that failed to fledge any offspring were much more likely to disperse than females that reproduced successfully, and the probability of dispersal declined gradually with female age. The spatial scale in which swallows gather and process information appears to be much larger than for passerines that defend all-purpose territories.Dispersión Reproductiva y Filopatría en Tachycineta bicolorResumen. Para estudiar los patrones y los determinantes de la filopatría y la dispersión reproductiva en Tachycineta bicolor analizamos los registros de 356 machos y 1459 hembras capturados en más de un año reproductivo en los alrededores de Ithaca, New York. De estas capturas, sólo el 4% de los machos y el 14% de las hembras reproductivas se dispersaron a un nuevo sitio de cría. Con nuestra combinación de áreas de estudio intensivas en el Condado de Tompkins, New York, y los esfuerzos de colaboradores voluntarios que anillaron aves a lo largo de New York y los estados circundantes, pudimos haber detectado eventos de dispersión a más de 400 km desde el sitio de cría inicial. Exámenes aleatorizados revelaron, sin embargo, que las aves reproductivas se dispersaron a distancias mucho más cortas que las que se podrían haber detectado. Análisis detallados de recapturas en el Condado de Tompkins mostraron que en un rango de distancias de 22 km, las probabilidades de dispersión a un nuevo sitio de cría disminuyeron con la distancia desde el sitio de cría original. Las hembras que fracasaron en la cría de pichones presentaron una probabilidad de dispersarse mucho mayor que las hembras que se reprodujeron exitosamente, y la probabilidad de dispersión disminuyó gradualmente con la edad de la hembra. La escala espacial a la que T. bicolor recoge y procesa información parece ser mucho más grande que la de aves paserinas que defienden territorios de uso múltiple.

Strategic adjustment of parental care in tree swallows: life-history trade-offs and the role of glucocorticoids

“…These two sites differ in the length of the breeding season (May to July in Ontario and March to July in NC). Tree swallows have high breeding site fidelity, and so return to the breeding population is often used as a proxy of annual survival [34]. In the NC population, return rates are around 50% for females (51% in 2015), which is higher than in the Ontario population (average 22% between 1975 and 2012, range 10–45%), or than has been found in other studies comparing southern and northern populations of tree swallows [15].…”

“…Tree swallows in our southern population in North Carolina have higher annual return rates—a robust proxy for annual survival in this highly philopatric species [34]—and a longer breeding season that in some instances even allows birds to raise a second brood (M.S. and Ç.A.…”

Effect of current reproduction on apparent survival, breeding dispersal, and future reproduction in barn swallows assessed by multistate capture–recapture models

“…Apart from a possible impact of current reproduction, breeding dispersal and survival are very likely to be affected by the sex and age of the individuals. In birds, breeding dispersal probability tends to be lower in males than in females and to decrease with age (Greenwood & Harvey 1982; Switzer 1993; Winkler et al . 2004).…”

The natal dispersal of tree swallows in a continuous mainland environment

“…Boxes were established at Experimental Ponds Unit 2 (128 boxes) in 1989, and on Cornell farm land at the top of Mt Pleasant (Unit 4: 60 boxes) in 1991 and along Hanshaw Road. (Unit 5: 22 boxes) in 1993 (see map in Winkler et al . 2004).…”

“…Murray 1967; Waser 1985), and we created a similar exponential null distribution by regressing the overall observed log probabilities of capture on distance and using the slope and intercept of this regression to parameterize the null distribution. Note that in this paper, in the interest of comparability, we use a one‐parameter exponential model, with a steeper drop‐off in probability of settlement with distance than in the two‐parameter exponential null used in Winkler et al . (2004).…”