1981), the selection for this will be strong. As winter survival depends on effective foraging (Jansson et al. Here, winter conditions can be harsh and, in cold winters, mortality will be high. Most parids are non-migratory and spend the winter in boreal or temperate zones.

This is logical if one considers that the species in this family possess relatively large brains compared to most other passerines (Lefebvre and Boogert 2010). Shettleworth 1983) and others the ability to use tools or a high ability to explore novel food sources such as sealed milk bottles (Fisher and Hinde 1949 Gosler and Clement 2007). Relative to other small passerines, they are known to possess foraging techniques that are cognitively advanced for example, some species have a large spatial memory capacity for cached food (e.g. Many species in the passerine family Paridae (tits, titmice and chickadees) are well known to people in the northern hemisphere as they are common visitors to bird feeders and frequently nest close to humans. the ability to visualise the cache from the hoarder’s perspective. For example, the latter must be done from a distance and hence may require the ability to adopt an allocentric perspective, i.e. Why should a marsh tit that memorises hundreds of their own caches in the field bother with the difficult task of memorising other individuals’ caches? We argue that the close-up memorisation procedure that marsh tits use at their own caches may be a different type of observational learning than memorisation of caches made by others. The marsh tits showed no evidence of such observational memorization ability, and we believe that such ability is more useful for a non-hoarding species. After a retention interval of 1 or 24 h, we allowed the observer to enter the arena and search for the caches. We allowed caged marsh tits to observe a caching conspecific in a specially designed indoor arena.

Here, we tested marsh tits in the same experimental set-up as where we previously have tested great tits. The other possibility is that this ability is general in the parid family. As great tits are explorative in nature and unusually good learners, it is possible that such “memorisation of caches from a distance” is a unique ability of theirs. We have previously demonstrated that great tits are able to memorise positions of caches they have observed marsh tits make and later return and steal the food. The perhaps most well-known species in the family, the great tit Parus major, does not store food itself but is skilled in stealing caches from the other species. Many species in the family Paridae, such as marsh tits Poecile palustris, are large-scale scatter hoarders of food that make cryptic caches and disperse these in large year-round territories.

The long dark cache