The influence of weather on avian spring migration phenology: What, where and when?

Abstract

Over the past decades, spring arrival and passage of most short‐ and medium‐distance migrating birds in the Northern Hemisphere have advanced. Changes in spring temperature at the passage or arrival area have been most frequently shown to be related to these changes in spring migration phenology. In most studies, preliminary assumptions are made on both the spatial location and the specific time frame of the weather influencing spring migration phenology. We performed a spatially explicit time‐window analysis of the effect of weather on mean spring passage dates of nine short‐ and medium‐distance passerines. We analysed data from standardized daily captures at the Helgoland (Germany) constant‐effort site, in combination with gridded daily temperature, precipitation and wind data from the NCEP data set over a 55‐year period (1960–2014), across the whole of West Europe and North Africa. Although we allowed for a time window of any length at any location, nevertheless incorporating various measures to avoid spurious correlations, time windows at the likely wintering or spring stopover grounds were almost exclusively selected as the best predicting variables (96%–100% of identified variables). The weather variables at the wintering and stopover grounds explain up to 77% of the interannual variability in spring passage. Yet, the response of spring migration phenology to weather at the winter or stopover areas does not fully explain the observed trends. Spring migration phenology is, hence, strongly driven by weather at the wintering and stopover grounds, but additional mechanisms are needed to fully explain the advancement of spring migration. Our results also clearly show that previously illustrated correlations, or the lack thereof, between spring migration phenology and weather at the passage or arrival location are due to spatio‐temporal correlations in the weather data. This spatial mismatch might have led to false conclusions, especially the further away the wintering or stopover sites are.

Leave Earlier or Travel Faster? Optimal Mechanisms for Managing Arrival Time in Migratory Songbirds

“…For example, our model predicts sex differences in migration speed to be greater for longer distance migrants or under better fueling conditions, but such information on these and selection agents are generally unavailable. Moreover, environmental variables such as temperature or weather conditions can serve as cues for, or directly affect, migration traits (Ahola et al, 2004;Both et al, 2005;Marra et al, 2005;Knudsen et al, 2011;Haest et al, 2018). Seasonal carry-over effects can also influence phenology (Marra et al, 1998;Gow et al, 2019).…”

The effect of weather on the decision to migrate from stopover sites by autumn-migrating ducks

“…As such, there was likely error associated with the spatial disconnect between the stopover site of interest and the site at which weather data were collected. There may have been additional unexplained variation associated with a “contrast effect,” [ 8 , 55 , 56 ] which results in higher departure probabilities when favorable conditions follow unfavorable conditions (i.e., high contrast) rather than similar favorable ones (i.e., low contrast). We did not attempt to model this effect due to its high correlation with weather variables [ 11 ].…”

“…During autumn, however, birds seem to rely more on external factors, such as food availability, predation risk, social context, and weather [ 7 ]. We contend that examining the relationships between these external factors and migratory responses can provide insight into which factors are important to specific taxa at which times and in which places [ 8 , 9 ].…”

The Potential Role of Migratory Birds in the Rapid Spread of Ticks and Tick-Borne Pathogens in the Changing Climatic and Environmental Conditions in Europe

“…The migratory behaviour of birds is triggered by many interacting exogenous factors, such as the photoperiod, temperature, and habitat food resources as well as endogenous factors (genetic traits, hormones) [79][80][81]. Climate and weather changes influence the length of birds' stay in wintering grounds [82,83] and the course of the seasonal migrations, e.g., the choice of time, place, and length of stopover necessary to rest and replenish energy reserves [81,[84][85][86][87][88]. The migratory behaviour of birds also depends on human activity, which contributes to the urbanization of large areas that used to be birds' habitats, drainage of habitats, and reduction of the surface of swamp areas and food resources in habitats.…”