Among animals there is a widespread behaviour called "communal roosting" - that is, to gather in groups for a period of rest. The reasons to explain this behaviour vary. However, some popular explanations for birds include that it acts as an anti-predator adaptation, a buffer against adverse weather conditions, and/or an information centre. Communal roosting seems to be especially common in birds; hundreds of species have been recorded to roost communally at least during certain periods of the year.

One such species in the Corvidae family is the Jackdaw (Corvus monedula). Breeding is done in single pairs or loosely connected colonies, often utilising e.g. hollows in trees, crevices and chimneys. From early autumn through winter, to the onset of next year's spring, jackdaws often gather in large numbers in cities for communal roosting, after the daily forage for food in the country-side.

Inventory the city of Linköping twice (autumn + winter) for communally roosting jackdaws. Map roost sites, compare conditions at roosts to those at a set of randomised zero-sites without roosting birds. Also, collect data on flight lines usage into the city, as well as the flux of individuals between roosts.

Based on earlier studies from elsewhere, I made the following assumptions before-hand:

1. Roosts would be high off the ground, surrounded by high buildings, close to foraging/green areas,
    
2. The majority of incoming individuals would come from the west and the east, respectively, due to extant areas of suitable feeding grounds,
    
3. High trees in parks and courtyards would dominate as roost sites,
    
4. The chosen schedule for flight lines observation would be very accurate,
    
5. There would be little or no movement of individuals between roosts during the night, and
    
6. There would be a clear seasonal difference with more individuals mid-winter than in the autumn, due to the ambient conditions

Why is this interesting?

Because jackdaws are sometimes considered a nuisance, my results could perhaps be used in the management of the species, when it comes to future planning of cities similar to Linköping.