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The fact that birds, despite their great vagility, are often absent from small or isolated patches of habitat has puzzled ecologists for decades. Landscape ecologists interested in birds generally focus on entire communities. As a result, there is a sizeable body of literature on relationships between Parids and edges, patches, and landscapes. While that literature is mainly based on species distribution data, it does provide useful background information that may help us understand challenges that Parids face when they move through landscapes. A cursory look at the Parid-versus-landscape literature shows that, although very similar in appearance and life history, Parids exhibit a great diversity of responses to the challenges posed by habitat pattern and isolation. This chapter uses meta-analysis to study Parid habitat use at three spatial scales — edges, patches, and landscapes. The focus then shifts to how landscape features, particularly the behavioural response of black-capped and boreal chickadees to gaps and forest corridors, influence interpatch dispersion and its potential for metapopulation dynamics.

Many North American parids have ranges that expose them to temperate winter seasons. Chickadees and titmice possess several physiological and behavioural adaptations that allow them to manage the reduced food supply and high thermoregulatory demands of this environment. Yet, increased habitat fragmentation posed by agricultural and urban expansion also presents a further stress to these populations. This chapter reviews research on physiological adaptations to reduced temperatures, and then addresses how microclimate change induced by habitat fragmentation can affect the response potential of over-wintering birds. These evolved responses have been investigated in chickadees and tufted titmice in isolated woodlots in agricultural landscapes, where fragmentation and patch size greatly alter the microclimate to which species are exposed.

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.

In comparing studies of Parid ecology, evolution, and behaviour that have been carried out in Eurasia and North America it becomes clear that there seem to be two essential impeding factors: differences in species' biology and the possibility for carrying out long-term studies. Differences in Parid evolution and natural history between North America and Eurasia have often dictated the types of research questions that can be addressed. The two main species that have been studied in Eurasia (great and blue tit) are at the base of the Parid tree, while all North American species are the result of two invasions 3.5 and 4 million years ago. North American Parids, therefore, belong to more derived clades. Great and blue tit, the primary study species that European scientists have been studying as model species for more than fifty years may, after all, not be representative for all tits and chickadees. To a large extent the variations in the types of studies conducted among great and blue tit (largely studied in Europe) on the one hand, and other Parids on the other hand (largely studied in North America and in northern Europe) are driven by the fact that when entire populations breed at high densities in artificial nest boxes it becomes much easier to collect detailed information, especially on reproduction, on large number of pairs.

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 discusses the fine-scale regulation of the timing of clutch initiation and fertility in Parids. This topic, which is the subject of long-term research studies on Eurasian tits and, recently, North American chickadees, considers the interaction between annual variation in weather patterns and food availability in regulating seasonal and individual variation in nest timing. Evidence from a variety of populations of tits reveals that clutch initiation is determined by a hierarchy of cues. Photoperiod regulates timing at the coarsest level, while temperature and food availability fine tune the onset of egg-laying within the year. There is ample evidence that females face costs in a number of fitness components if their reproduction is not optimally timed. In spite of all this evidence, some questions remain concerning the inter-relationships of timing, temperature, and female quality. It is also not clear why selection has not weeded out females that breed late. The current emphasis on the relationship of female timing to climate change may reveal the ability of populations to respond to selection for earlier laying and their changing sensitivity to the relevant cues.