Valencia: bird ringing sheds light on wetland warbler survival

For many Honeyguiders, one of the highlights of our March Valencia trip is to attend a bird ringing session at Pego Marshes Natural Park. Our local guide, Pau Lucio, and colleagues from Grupo de Anillamiento Pit-Roig (also on Facebook) have been managing a constant effort ringing site since 2004.

Bluethroat at Pego Marshes, with local Honeyguide leader Pau Lucio.

The site provides much information to study the reedbed passerine community, which includes some lovely wintering species: bluethroat, reed bunting, penduline tit and Cetti’s warbler, among others.

Kingfisher.

Reed bunting.

Cetti's warbler.

However, stealing the spotlight is the moustached warbler, for which Pego Marshes has the second largest Spanish breeding population. Numbers increase in winter with the arrival of many French breeding birds.

Pau and colleagues are about to publish a scientific paper comparing how climate change affects the breeding population of the moustached warbler and the reed warbler across Spain. To do that, they used thousands of bird ringing data from 51 ringing sites across Spain.

They found that the number of moustached warbler offspring is negatively affected by the rise in temperatures and late winter/early spring storms that affect incubation and chick rearing. In contrast, the reed warbler appears resilient to the negative impacts of precipitation, while an increase in temperatures seems to have a positive effect on the reproductive success, leading to a higher number of offspring.

Moustached warbler.

These results align with other papers that show that climate change affects more specialist species – ones that need a more specific habitat – with a fragmented distribution, in this case the moustached warbler, and affects less the generalist bird with a wide distribution, here reed warblers.

During the ringing session on the holiday, Pau will explain the research he is involved with. The photos of birds were all ringed during previous Honeyguide visits.

Honeyguide’s wildlife holiday in Valencia in 2024 runs from 8 to 15 March. More information on http://www.honeyguide.co.uk/wildlife-holidays/Valencia.html

Information provided by Pau Lucio. Photos by Pau, except Pau with bluethroat by Chris Durdin. More ringing photos from a previous trip here on Facebook, including penduline tit, sedge warbler and chiffchaff.