Climate Change, Spring Temperatures, and Timing of Breeding of Tree Swallows (Tachycineta bicolor) in Southern Ontario

The Auk ◽  
2003 ◽  
Vol 120 (3) ◽  
pp. 607-618
The Auk ◽  
2003 ◽  
Vol 120 (3) ◽  
pp. 607-618 ◽  
Author(s):  
David J. T. Hussell

AbstractSeveral European studies have indicated advances in breeding dates of birds in the last 30 years, which authors attributed to climate change. In North America, Dunn and Winkler (1999) reported a continent-wide advance of five to nine days in breeding dates of Tree Swallows (Tachycineta bicolor) between 1959 and 1991. I present results of an intensive study of Tree Swallows breeding on and near Long Point, Ontario, at four sites monitored 1969–2001, 1977–1986, 1978–2001, and 1987–2001. Local air temperatures varied among sites, according to distance from Lake Erie, but there was no significant regional trend in April and May temperatures between 1969 and 2000. Median and 10th percentile dates of clutch initiation by females that were at least two years old varied among years by up to 20 days overall and 18 days within sites, and differed by 0–14 days between sites in the same year. There were no significant differences in average timing of laying among the 1970–1980, 1980–1990, and 1990–2000 periods. Nevertheless, there was a significant trend towards earlier laying in 1990–2000, which was attributable to exceptionally early laying and warm May weather in 1998–2001. Across all sites, median dates of clutch initiation were strongly correlated with average daily maximum temperatures in the first four, five-day periods in May, but clutches at one site were initiated three days earlier than predicted by temperatures alone. I estimate that climate warming of 5°C in May could result in an average advance of about seven days in the median date of laying of Tree Swallows at those sites. My results indicate that spring temperatures are strongly correlated with timing of laying, but show that spring temperatures have not increased in the Long Point region and timing of the breeding season has not advanced throughout North America.


Oecologia ◽  
2020 ◽  
Vol 192 (3) ◽  
pp. 713-722 ◽  
Author(s):  
Amelia R. Cox ◽  
Raleigh J. Robertson ◽  
Wallace B. Rendell ◽  
Frances Bonier

1991 ◽  
Vol 69 (10) ◽  
pp. 2540-2547 ◽  
Author(s):  
Nathaniel T. Wheelwright ◽  
Joanna Leary ◽  
Caragh Fitzgerald

We investigated the effect of brood size on nestling growth and survival, parental survival, and future fecundity in tree swallows (Tachycineta bicolor) over a 4-year period (1987–1990) in an effort to understand whether reproductive trade-offs limit clutch size in birds. In addition to examining naturally varying brood sizes in a population on Kent Island, New Brunswick, Canada, we experimentally modified brood sizes, increasing or decreasing the reproductive burdens of females by two offspring. Unlike previous studies, broods of the same females were enlarged or reduced in up to 3 successive years in a search for evidence of cumulative costs of reproduction that might go undetected by a single brood manipulation. Neither observation nor experiment supported the existence of a trade-off between offspring quality and quantity, in contrast with the predictions of life-history theory. Nestling wing length, mass, and tarsus length were unrelated to brood size. Although differences between means were in the direction predicted, few differences were statistically significant, despite large sample sizes. Nestlings from small broods were no more likely to return as breeding adults than nestlings from large broods, but return rates of both groups were very low. Parental return rates were also independent of brood size, and there was no evidence of a negative effect of brood size on future fecundity (laying date, clutch size). Reproductive success, nestling size, and survival did not differ between treatments for females whose broods were manipulated in successive years. Within the range of brood sizes observed in this study, the life-history costs of feeding one or two additional nestlings in tree swallows appear to be slight and cannot explain observed clutch sizes. Costs not measured in this study, such as the production of eggs or postfledging parental care, may be more important in limiting clutch size in birds.


Biologia ◽  
2006 ◽  
Vol 61 (5) ◽  
Author(s):  
Zdravko Dolenec

AbstractIncreasing evidence suggests that climate change affects bird breeding phenology and other life-history traits of wildlife. This study is based on the mean spring temperatures (February, March, April) and laying dates of first eggs of the marsh tit Parus palustris. We collected data from 1984 to 2004 for the Mokrice area in NW Croatia. Correlation between laying date and mean spring temperatures was significant. The relationship between mean laying date (y) and air temperature (x) can be expressed as y = 44.69 − 2.08x. Results indicate that spring temperatures are a good predictor of timing of laying eggs. Such long-term data could than be used in order to assess the effects on biological systems if human activities influence climate.


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