Rare cross-species feeding observed in Heinola as willow tit feeds barn swallow chick

A willow tit was observed feeding a barn swallow chick in Heinola’s Kausa district on Thursday, a rare phenomenon in nature, Yle reports.

The barn swallow chick had left its nest and was stranded on a thin juniper branch, a spot its own parents appeared unable to reach. A willow tit, whose own chicks had died the previous day, began bringing insects to the chick as if it were her own.

The Vallasjoki family, who arrived at their cottage on Wednesday, first noticed the dead willow tit chicks beneath their nest. The next day, the female willow tit shifted her care to the surviving chick—of a different species entirely.

Aapo Salmela, a bird expert at BirdLife Finland, called such interspecies feeding extremely uncommon. Known scientifically as interspecific feeding, it typically occurs when a parent’s own brood has recently perished and another species’ nest is nearby. Evolutionarily, he noted, the behavior offers no benefit and may even be detrimental to the feeding bird.

More common is imprinting, where a chick bonds with a foster parent of another species, a phenomenon frequently seen in waterfowl.

A 2021 review found 186 documented cases of interspecies feeding across 107 bird species over 40 years, including instances of blackbirds feeding great reed warbler chicks. The cuckoo, which lays its eggs in other birds’ nests, is a well-known example of cross-species parental care.

The willow tit’s efforts in Heinola were ultimately unsuccessful. The barn swallow chick was found dead Friday morning.