Pied Wagtail winter territories

In the last few weeks, two Pied Wagtails have been feeding around the pond in my local park, staying near each other, but not too close, one chasing the other every now and then. I have watched this before, and managed to get photos last year (top shot, East Park, 9th January 2023). This behaviour, of two Pied Wagtails 'teaming up' to defend a territory during the winter, is quite typical of the species, and it was studied in detail in the early 1980s by Nick Davies and A.I. Houston along the river Thames near Oxford. The feeding territories studied were along the water, on both banks, where the wagtails pick small flies, spiders and beetles often washed onto the mud at the waterline, circuiting along one bank, then the other. The territory owner, usually an adult male, occasionally accepted an intruder as a 'satellite', often a female or juvenile, especially when there were enough resources to share. The satellite appeased the owner with a specific display, with bill and tail pointing up. The owners were more likely to tolerate the satellite when food was more abundant.

Appeasement posture of female White Wagtail (from Zahavi, 1971).

Although the presence of the satellite meant food resources needed to be shared in the territory, the satellite also helped with territory defence. The territories were defended vigorously, as the food resources depleted as the wagtails fed on the washed out insects, so intruders would reduce the feeding rate of the territory holders. Territory defence also involved calls, both of the intruding bird and of the residents. Davies and Houston quantified the benefits and costs of territory defence and accepting a satellite depending on the quantity of available resources.

It is clear that Pied Wagtails have a very flexible social behaviour. They gather in large, compact communal roosts during the night. Also, in places or at times where there is a glut of resources, for example during ploughing time, or emergence of insects, territory defence may break up and the wagtails might gather in loose flocks with little aggression.

In these photos of the East Park pair (above and top shot), the differences in plumage between the male (at the front) and the female behind are apparent.

I couldn't take a photo with both individuals from the 7th December at Pearson park together, but the difference in plumage indicates a male (above)...

... and a juvenile (below) is also clear. Note the juvenile's yellowish face.

More information

Davies, N. B. Food, Flocking and Territorial Behaviour of the Pied Wagtail (Motacilla alba yarrellii Gould) in Winter. J. Anim. Ecol. 45, 235–253 (1976).   

Zahavi, A. The social behavior of the White Wagtail Motacilla alba alba wintering in Israel. Ibis 113, 203–211 (2008).

Making the best of bad weather

Birds have a range of behaviours to cope with the cold. Many - Swallows, Cuckoo, many warblers - avoid it altogether by migrating to warmer latitudes well ahead of winter, these are birds exploiting resources that are virtually non-existing in the winter such as caterpillars or flying insects. Others undergo more regional migrations, often depending on the local conditions. Here, surprisingly, there are many British species, which move south to the continent, and at the same time come to the UK from colder areas like Fennoscandia, these would include the Robin or the Blackcap. Yet another group of species simply change their habitat preferences. Some species that are found in mountain areas move down to the plains in the winter, species that feed on freshwater lakes and ponds in the summer move to the coast, where water does not freeze in the winter (Grebes and Kingfishers do this). There are a fourth group of species which change their food habits with cold weather. The Blackbird and other thrushes switch to feeding on berries when the ground is too hard to hunt for earthworms. I probably haven't exhausted the options and several of them are not mutually exclusive. For example, the Swift, a summer migrant from Africa, also undergoes substantial regional migrations in avoidance of poor weather. In addition, some of these options are only taken depending on the local conditions. The Waxwing's irruptions, when birds normally inhabitants of northern Europe, reach the UK and western Europe, happen in response to poor berry crops in the rowan of their native forests, and then to happen at irregular intervals. The last one of such invasions happened during the winter of 2008-2009.
  In the last few days, I have noticed couple of species which I don't see very often within the city have become more common. One of them is the Pied Wagtail, the other the Redwing. The first one belong to the  habitat switchers, the Pied Wagtail is most often found in gardens and towns during the winter. With its constant tail bobbing and its frantic running and direction-changing motion in chase of minute insects and bugs, to get a decent photo in the gloomy dark days we've had lately is a challenge. The Redwings, which migrate into the UK in the winter from northern Europe, feed on grassy areas - or berries - in loose flocks, they are quite wary and the photos are also not good.

Two Redwings