A recent survey in Spain has raised alarm bells for the European population of Lesser Kestrel, with the species experiencing a continuing decline despite targeted conservation efforts.
Lesser Kestrel was categorised as Vulnerable by the IUCN due to a significant fall in numbers between the 1950s and 1990s, but the species has enjoyed Least Concern status from 2011.
However, a new study reveals a staggering decline of 6% per year in Spain since 2012. The country hosts around 40% of the European breeding population.
Lesser Kestrel numbers have fallen in the study area since their peak in 2012, despite ongoing conservation measures (Marc FASOL).
Rare raptor
The decline has worried conservationists as it continues after the establishment of the European Union's Natura 2000 network, which was implemented to protect biodiversity. Within this framework, species-specific conservation efforts such as captive breeding and nestbox provision were targeted at Lesser Kestrel populations, but the ongoing population decline has left experts questioning the efficacy of current techniques.
The study, recently published in Ibis, focused on colonies in La Mancha, Spain, seeking to understand the causes behind the Lesser Kestrel decline and gauge how well conservation measures have been working.
The research led by José Miguel Aparicio found that the population at La Mancha had fallen by 39.4% since 2003. The data showed an annual decline of 6% since the population peak in 2012, mirroring trends across Spain.
Insect declines
The main driver of the decline is thought to be the reduced availability of large grasshoppers and crickets, a staple for Lesser Kestrel nestlings. The loss of pasture and herbaceous crops compounded the decline in prey availability. The deterioration or demolition of old buildings where the kestrels breed hasn't helped, reducing the availability of potential nest sites.
The study noted an apparent negative impacting on kestrel colony size with increasing rabbit populations. Overgrazing by rabbits has the potential to influence large insect abundance, but the team suspected Lesser Kestrels might be taken by larger birds of prey drawn to the area by the increased rabbit numbers.
While Natura 2000 network played its part in slowing down land use changes, the influence of nestbox provision has remained unclear. The study suggested that further research should investigate the impact of nestboxes on other species and delve deeper into the link between rabbits and kestrel colonies.
Reference
Causes of the recent decline of a Lesser Kestrel (Falco naumanni) population under an enhanced conservation scenario. Aparicio, J M, Muñoz, A, Cordero, P J, & Bonal, R. 2023. IBIS. DOI: 10.1111/ibi.13145.
