Hydrology influences breeding time in the white-throated dipper

Abstract

Background Earlier breeding is one of the strongest responses to global change in birds and is a key factor determining reproductive success. In most studies of climate effects, the focus has been on large-scale environmental indices or temperature averaged over large geographical areas, neglecting that animals are affected by the local conditions in their home ranges. In riverine ecosystems, climate change is altering the flow regime, in addition to changes resulting from the increasing demand for renewable and clean hydropower. Together with increasing temperatures, this can lead to shifts in the time window available for successful breeding of birds associated with the riverine habitat. Here, we investigated specifically how the environmental conditions at the territory level influence timing of breeding in a passerine bird with an aquatic lifestyle, the white-throated dipper Cinclus cinclus. We relate daily river discharge and other important hydrological parameters, to a long-term dataset of breeding phenology (1978–2015) in a natural river system. Results Dippers bred earlier when winter river discharge and groundwater levels in the weeks prior to breeding were high, and when there was little snow in the catchment area. Breeding was also earlier at lower altitudes, although the effect dramatically declined over the period. This suggests that territories at higher altitudes had more open water in winter later in the study period, which permitted early breeding also here. Unexpectedly, the largest effect inducing earlier breeding time was territory river discharge during the winter months and not immediately prior to breeding. The territory river discharge also increased during the study period. Conclusions The observed earlier breeding can thus be interpreted as a response to climate change. Measuring environmental variation at the scale of the territory thus provides detailed information about the interactions between organisms and the abiotic environment.

Spatial variation in avian phenological response to climate change linked to tree health

“…Nevertheless, where they occur, adaptive habitat choice decisions may have profound population-level consequences, buffering populations against the effects of climate change and potentially preventing population extinction, as well as providing additional time for the evolutionary change that is likely to be key in enabling effective long-term responses to climate change 50,75 . Despite this, little work has explored fine-scale spatial heterogeneity in climate change responses (but see 76,77 ), and thus studies examining changes in habitat selection behaviour in response to climate change, and its fitness consequences, are extremely rare (but see 78,79 ).…”

Long‐term annual and spatial variation of polygyny in the white‐throated dipper (Cinclus cinclus)

“…The males may display far away from the first territory to escape aggression from the first female (Slagsvold et al, 1999 ) because females are able to locate their own mate from at long distances from his song (Lampe & Slagsvold, 1998 ). In this species, and in many other birds with biparental care, the secondary females may suffer reduced breeding success, yet it may still pay off to attempt nesting if the alternative is not breeding at all (Kempenaers, 1994 ; Nilsson et al, 2020 ; Slagsvold & Lifjeld, 1994 ).…”