New Farm Roofs Locked Owls Out. Naturalists Are Cutting Them a Spare Key

In the countryside around Vic, in Catalonia, naturalists are encouraging farmers to put in a roof tile that does more than keep the rain out. It has a hole in it on purpose, so a little owl can move in.

The tiles come from the Grup de Naturalistes d’Osona (GNO), a local naturalists’ group. It runs a campaign asking homeowners and farmers to fit the tiles into their roofs, giving the little owl (Athene noctua) places to shelter and raise chicks.¹ According to a July 2025 report in El 9 Nou, a spring census found a strong decline in the little owl population, and a lack of nests is a main cause.¹

That matters because the little owl is a protected species in Catalonia. It is listed as vulnerable under Decree 172/2022, one step before the “endangered” category.¹³

Why a new roof is bad news for an owl

When farmhouse roofs are replaced, the old natural holes the owl used go with them.² Carles Martorell of the GNO described the problem in NacióDigital, saying the tile appeals to people who restore farmhouses:²

“It interests architects and builders who restore farmhouses, because when the roof was replaced, the owl lost those natural holes in the old houses and couldn’t make its nest.” (translated from Catalan)

In other words, a new roof is good for the family underneath it and a closed door for the owl that used to nest there. The tile, a design devised by the naturalists, slots into the roof of a farmhouse, barn or hayloft and puts a nesting hole back.²

How the tiles get on the roofs

The GNO offers the tiles to people willing to install them and shows them how to place a tile so it has the best chance of working. It also teaches them how to check whether an owl has moved in. Farmland is the ideal setting.¹

The project is a joint effort between the GNO and Grup Natura Sterna. Tiles go to owners and farmers in Osona, Bages and Baix Empordà. The idea started with the Calldetenes-Osona bird ringing group (ringing means fitting birds with small leg bands) and was then tested and improved by the GNO.³

The 10th Delta Birding Festival, held in 2024, donated its ticket-sale proceeds to the project, which goes by the name “Apadrina una Teula Mussolera”. The money paid for a mold and the production of 80 tiles.³⁴

Martorell and Jaume Ramot presented the project at the festival. Their talk described the little owl’s decline as alarming and made the case that better nest sites are one problem people can fix right away.⁴

The tiles are not the GNO’s only effort. In October 2024 the group installed 10 nest boxes between Balenyà and Tona, after detecting a decline in little owls in the southern part of the Vic plain, probably because good nesting cavities were scarce.⁵

Early signs of tenants

Martorell told El 9 Nou that the idea has been very well received, and that in the two years tiles have been installed, there have already been occupations.¹