Broad‐front migration leads to strong migratory connectivity in the lesser kestrel (Falco naumanni)

Abstract

Aim: Migratory animals regularly move between often distant breeding and non-breeding ranges. Knowledge about how these ranges are linked by movements of individuals from different populations is crucial for unravelling temporal variability in population spatial structuring and for identifying environmental drivers of population dynamics acting at different spatio-temporal scales. We performed a large-scale individual-based migration tracking study of the lesser kestrel (Falco naumanni), an Afro-Palearctic migratory raptor, to determine the patterns of migratory connectivity of European breeding populations. Location: Europe, Africa. Methods: Migration data were recorded using different devices (geolocators, Argos PTTs, GPS loggers) from 87 individuals breeding in the three core European populations, located in the Iberian, Italian and Balkan peninsulas. We estimated connectivity by the Mantel correlation coefficient (rM), and computed both the degree of separation between the non-breeding areas of individuals from the same population (i.e. the population spread) and the relative size of the non-breeding range (i.e. the non-breeding range spread). Results: European lesser kestrels migrated on a broad-front across the Mediterranean Sea and Sahara Desert, with different populations using different routes. Iberian birds migrated to western Sahel (Senegal, Mauritania, western Mali), Balkan birds migrated chiefly to central-eastern Sahel (Niger, Nigeria, Chad), whereas Italian ones spread from eastern Mali to Nigeria. Spatial differentiation of non-breeding areas led to a strong migratory connectivity (rM = 0.58), associated with a relatively high population (637 km) and non-breeding range (1149 km) spread. Main conclusions: Our comprehensive analysis of the non-breeding distribution of European lesser kestrel populations revealed a strong migratory connectivity, a rare occurrence in long-distance avian migrants. The geographic conformation of the species' breeding and non-breeding ranges, together with broad-front migration across ecological barriers, promoted the differentiation of migratory routes and non-breeding areas. Strong connectivity could then arise because of both high population spread and broad non-breeding range.

Flexibility in Migratory Behaviour of a Flight Generalist: Migrate Day and Night, Sprinting Across Ecological Barriers 

“…In accordance with previous tracking studies on the lesser kestrel, individuals completed their migration faster during the post-breeding relative to the pre-breeding migration 40 . We modelled to what extend wind conditions sex-speci c and other seasonal drivers could explain differences in performance.…”

“…After accounting for tag malfunctions and individuals that did not return to the colony the year after tagging, we compiled data from 72 adults who completed their migration from Spain (n = 60) and Italy (n = 12) to Africa either along the East Atlantic or the Central Mediterranean migration yways. Data of some of these individuals, 15 from Spain and 12 from Italy, had previously been used to analyse summer and winter population connectivity 40 . We included in our analyses 70 adults (40 females and 30 males) that provided 75 post-breeding and 66 pre-breeding migration tracks.…”

Mining citizen science data to explore stopover sites and spatiotemporal variation in migration patterns of the red-footed falcon

“…2018 ). Such a pattern has also been described for the closely related Lesser Kestrel ( Sarà et al. 2019 ).…”

Using GPS tracking and stable multi-isotopes for estimating habitat use and winter range in Palearctic ospreys

“…Advances in technology and chemistry provided tools for gathering essential information on individual movements and connectivity between breeding, wintering and stopover sites (Webster et al 2002 ; Trierweiler et al 2014 ; Choi et al 2020 ). Satellite (GPS) tracking reveals wintering grounds and the migratory routes (tracks) followed between breeding and non-breeding areas with high accuracy and precision (Phipps et al 2019 ; Sarà et al 2019 ). Carbon, Nitrogen, Sulphur, Deuterium and Oxygen Stable Isotope Analyses (SIA), measured in feathers or other tissues, allowed further determination of seasonal habitat use and diet (Hobson 1999 ; Atkinson et al 2005 ; Blight et al 2014 ; Hobson and Wassenaar 2018 ).…”