Not everyone is shrinking: Sand Martins are getting bigger

Many bird species are getting smaller as the climate warms — but not all of them.

In our new paper in Ibis, Aldo Tamietti and I show that a Sand Martin (Riparia riparia) population breeding in northwestern Italy has, over more than two decades of standardised monitoring, increased in both body mass and wing length. This is the opposite of the widely reported “shrinking-bird” pattern.

The result reminds us that the global picture is built from very different local stories, and that long-term, standardised datasets — often maintained by ringers and small ornithological stations — are essential to tell those stories apart from noise.

🔗 Read the paper: Masoero & Tamietti (2025), Ibis, DOI 10.1111/ibi.70020.

Data and analysis scripts archived on the Open Science Framework.