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Habitat destruction and fragmentation poses one of the most serious threats to biodiversity in conservation biology. What distinguishes habitat fragments is that the intervening gaps are often vegetated, rather than open expanses of ocean. This intervening habitat, referred to as ‘the matrix’, differs in species composition or age and/or structure of the vegetation so as to be sufficiently distinct from the remnant habitat islands they surround. Matrix habitat is considered less hospitable for remnant-dwelling species, yet terrestrial matrices may not be quite as impermeable as open oceans. This chapter addresses the potential for breeding in altered habitats, such as those found in managed habitat matrices that separate remnant, native forest. Using studies on both Eurasian tits and North American chickadees, analyses investigating breeding in forests of divergent habitat quality are paralleled with proposed management of matrix vegetation as alternative breeding habitat for matrix-tolerating species.

This introduction presents an overview of the North American Paridae, and details the general lack of agreement as to whether the distinct lineages among these birds worldwide should be considered as distinct, separate genera (as adopted by the American Ornithologist Union in North America in the 1990s), or whether these should be merely subgenera (the prevalent view until recently on the other side of the Atlantic). This disagreement led to the rather confusing situation in which the black-capped chickadee remains Parus atricapillus in European journals, while having undergone the unfortunate and convoluted journey through Poecile atricapilla to Poecile atricapillus in North American journals. North American chickadees can be further divided into two phenotypically distinct groups: those with black caps and whistled songs (the black-capped, Carolina, mountain and Mexican chickadees); and those with brown or grey caps, which typically lack whistled songs (the chestnut-backed, boreal chickadees, and Siberian tits). Although three subspecies of chestnut-backed chickadees are recognized, microsatellite analysis indicates that there are actually four genetically distinct populations now alive: two in British Columbia (Queen Charlotte Islands, and south-eastern B.C.); one confined to Alaska (central Alaska); and a large coastal group.

This chapter investigates the structural aspects of the avian brain, and how this can influence spatial memory. Using cross-species comparisons within the Paridae and comparing Parids to other species, general spatial abilities of chickadees in food storing and other contexts are reviewed. The ability to form spatial memories is related to the structure, gene expression, and neurogenesis within the hippocampus. Chickadees and tits have made an unexpected contribution to our understanding of spatial ability and the hippocampus because of their specialized food storing behaviour. The jury is still out on the question of whether spatial ability or spatial cognition is specialized in chickadees and tits. Some properties of spatial ability and spatial memory in food-storing birds are very similar to those of other species. One notable pattern is that food-storing birds may tend to solve foraging tasks spatially to a degree not found in other birds.

This chapter summarizes information from studies on the hybrid zone between black-capped and Carolina chickadees in southeastern Pennsylvania. The focus is on patterns of vocal variation in relation to among- and within-population genetic variation. Primary questions that are addressed include: the song and call types produced within this hybrid zone; whether the vocalization types are congruent with one another within individuals; and insights that might be derived from these patterns regarding mechanisms of hybridization in chickadees. Available information, and opportunities for further research, concerning patterns and mechanisms of hybridization among Parids of both North America and Eurasia is analyzed. The largest gap in understanding the behavioural ecology of hybridization in chickadees concerns dominance interactions and their relationships with both social pairing and extrapair mating. To date, no thorough field study of dominance relationships has been completed within any part of the contact zone.