Urban biodiversity in the Anthropocene.

The urbanisation process, which consists of the transformation of semi-natural and natural habitats to heavily modified habitats dominated by buildings and infrastructure such as roads, continues in response to an increasing human population and an increasing proportion of people inhabiting urban areas. The urbanisation process generally has negative impacts upon biodiversity, and as urban areas are expected to expand in the future, we need to acquire a better understanding of the ecological effects of urbanisation. In this Collection focusing on urban biodiversity, articles improve our understanding of the distribution of biodiversity between and within urban areas, whilst also seeking to understand the consequences of urbanisation for trophic cascades and genetic divergence.

Plumage and eggshell colouration covary with the level of sex-specific parental contributions to nest building in birds.

Interspecific variation in sex-specific contributions to prenatal parental care, including avian nest building, is becoming increasingly better understood as we amass more information on more species. We examined whether sex-specific nest building contributions covary with the colouration of parents and their eggs in 521 species of Western Palearctic birds. Having colourful plumage and laying colourful eggs are costly because of the deposition of pigments in feathers and eggs and/or forming costly nanostructural substrates in feathers, and so it might be expected that those costs covary with the costs of nest building at the level of individuals and/or across species to produce of a suite of codivergent traits.

Nest architecture influences host use by avian brood parasites and is shaped by coevolutionary dynamics.

Brood (social) parasites and their hosts exhibit a wide range of adaptations and counter-adaptations as part of their ongoing coevolutionary arms races. Obligate avian brood parasites are expected to use potential host species with more easily accessible nests, while potential hosts are expected to evade parasitism by building more concealed nests that are difficult for parasites to enter and in which to lay eggs. We used phylogenetically informed comparative analyses, a global database of the world's brood parasites, their host species, and the design of avian host and non-host nests (approx.

Why do some bird species incorporate more anthropogenic materials into their nests than others?

Many bird species incorporate anthropogenic materials (e.g. sweet wrappers, cigarette butts and plastic strings) into their nests.