Linking phenological events in migratory passerines with a changing climate: 50 years in the Laurel Highlands of Pennsylvania

Abstract

Advanced timing of both seasonal migration and reproduction in birds has been strongly associated with a warming climate for many bird species. Phenological responses to climate linking these stages may ultimately impact fitness. We analyzed five decades of banding data from 17 migratory bird species to investigate 1) how spring arrival related to timing of breeding, 2) if the interval between arrival and breeding has changed with increasing spring temperatures, and 3) whether arrival timing or breeding timing best predicted local productivity. Four of 17 species, all mid- to long-distance migrants, hatched young earlier in years when migrants arrived earlier to the breeding grounds (~1:1 day advancement). The interval between arrival on breeding grounds and appearance of juveniles shortened with warmer spring temperatures for 12 species (1–6 days for every 1°C increase) and over time for seven species (1–8 days per decade), suggesting that some migratory passerines adapt to climate change by laying more quickly after arrival or reducing the time from laying to fledging. We found more support for the former, that the rate of reproductive advancement was higher than that for arrival in warm years. Timing of spring arrival and breeding were both poor predictors of avian productivity for most migrants analyzed. Nevertheless, we found evidence that fitness benefits may occur from shifts to earlier spring arrival for the multi-brooded Song Sparrow. Our results uniquely demonstrate that co-occurring avian species are phenologically plastic in their response to climate change on their breeding grounds. If migrants continue to show a weaker response to temperatures during migration than breeding, and the window between arrival and optimal breeding shortens further, biological constraints to plasticity may limit the ability of species to adapt successfully to future warming.

Early Breeding Conditions Followed by Reduced Breeding Success Despite Timely Arrival in an Alpine Migratory Songbird

“…Within the same species, flexible adjustment to earlier springs seemed to be realised by shortening the arrival-breeding interval (Nicolau et al, 2021). McDermott and DeGroote (2017) analysed data on 17 migratory species, and found a positive relationship between earlier arrival at the breeding grounds and earlier breeding in four species, whereas in six species, the arrival-breeding interval shortened in warmer springs, as occurred in our Alpine wheatear population in 2020 (Figure 2B).…”

The effect of climate change on the duration of avian breeding seasons: a meta-analysis

“…As long-term changes in laying dates are related to body size [38], we also predict that small-bodied species will change the duration of their seasons more significantly in comparison with larger species [38,39]. Finally, previous studies suggested that long-distance migrants may be constrained in their phenological response to climate change [40][41][42][43], thus we may expect that the duration of their breeding season will change less across time, in comparison with short-distance migrants or sedentary species.…”

“…Therefore, our study may provide a new argument in support of the phenologymismatch hypothesis [71], which assumes that the rate of warming in the breeding and wintering areas need not to be correlated, causing a delayed departure from wintering sites and ecological mismatch at the breeding sites. Several other studies have also shown that although long-distance migrants have been arriving progressively earlier in response to climate warming [41,42] and the interval between arrival and breeding has shortened [40,43], their breeding phenology has been actually delayed in relation to plant or insect phenology [35,40,41].…”

Extrinsic factors, endocrine mechanisms, and behavioral indicators of migratory restlessness in wintering whooper swans (Cygnus cygnus)

“…This result suggests that air temperature was the main factor activating the endocrine control of spring migration in wintering whooper swans. Numerous studies have reported on the effects of photo period 5 , 11 – 14 or ambient temperature 42 – 47 on the spring migration of palae-arctic migrants. Since both parameters are inevitably linked—even in our study we found a strong correlation of both factors—it was proposed that both environmental factors influence the departure from wintering areas by influencing the endocrine control mechanisms 48 , 49 .…”