Restoration of Fragmented Landscapes for the Conservation of Birds: A General Framework and Specific Recommendations for Urbanizing Landscapes

Abstract

Humans fragment landscapes to the detriment of wildlife. We review why fragmentation is detrimental to wildlife (especially birds), review the effects of urbanization on birds inhabiting nearby native habitats, suggest how restoration ecologists can minimize these effects, and discuss future research needs. We emphasize the importance of individual fitness to determining community composition. This means that reproduction, survivorship, and dispersal (not simply community composition) must be maintained, restored, and monitored. We suggest that the severity of the effects of fragmentation are determined by (1) the natural disturbance regime, (2) the similarity of the anthropogenic matrix to the natural matrix, and (3) the persistence of the anthropogenic change. As a result, urbanization is likely to produce greater effects of fragmentation than either agriculture or timber harvest. Restoration ecologists, land managers, and urban planners can help maintain native birds in fragmented landscapes by a combination of short-and long-term actions designed to restore ecological function (not just shape and structure) to fragments, including: (1) maintaining native vegetation, deadwood, and other nesting structures in the fragment, (2) managing the landscape surrounding the fragment (matrix), not just the fragment, (3) making the matrix more like the native habitat fragments, (4) increasing the foliage height diversity within fragments, (5) designing buffers that reduce penetration of undesirable agents from the matrix, (6) recognizing that human activity is not compatible with interior conditions, (7) actively managing mammal populations in fragments, (8) discouraging open lawn on public and private property, (9) providing statutory recognition of the value of complexes of small wetlands, (10) integrating urban parks into the native habitat system, (11) anticipating urbanization and seeking creative ways to increase native habitat and manage it collectively, (12) reducing the growing effects of urbanization on once remote natural areas, (13) realizing that fragments may be best suited to conserve only a few species, (14) developing monitoring programs that measure fitness, and (15) developing a new educational paradigm.

A conceptual framework for the colonisation of urban areas: the blackbirdTurdus merulaas a case study

“…First, habitat modification is marked in urban areas, with the magnitude of change often exceeding that resulting from rural land-uses, such as logging and farming. Urban centres are characterised by highly fragmented habitat patches with a simple habitat structure and very low habitat diversity, although at small spatial scales habitat diversity may be markedly higher in suburban areas (Marzluff & Ewing, 2001;Grimm et al, 2008;Evans et al, 2009d). The magnitude of this divergence between urban and rural habitats is clearly regulated by human attitudes and socio-economic factors that determine: (i) the level of supplementary resource provision, such as avian nest sites and food, which can be an important influence on urban assemblages (Fuller et al, 2008;Davies et al, 2009;Evans et al, 2009d), (ii) levels of predation by humans (Vuorisalo et al, 2003) and their commensals, such as domestic cats (Baker et al, 2008;Sims et al, 2008), and (iii) the location of urban areas, which is likely to be non-random with regard to their ecological situations (e.g.…”

Extending large-scale forest inventories to assess urban forests

“…Urban forests average size is about 2.2 ha. These forest patches can play a significant role in the maintenance of biodiversity, by providing habitat and food for plant and animal species and facilitating their dispersal by contributing to biological connectivity in the urban landscape (Marzluff and Ewing 2001). Moreover, greenspaces and forest trees contribute to a number of environmental functions in urban environments such as the survival of urbandwelling species, like bird species (Sanesi et al 2009).…”

Measuring Landscape Connectivity in a Urban Area for Biological Conservation

“…The recent and ongoing destruction and degradation of vegetation pose a serious threat to the maintenance of biodiversity worldwide [1][2][3]. The loss and fragmentation of habitats, resulting from agricultural intensification, infrastructure networks, and urbanization, are considered to be the main driving forces in the current biodiversity crisis [4].…”

“…Habitat loss and fragmentation have changed community structures and have potentially or significantly changed important ecological processes, such as pollination, nutrient cycling, seed dispersal, and predation relationships, and are therefore important reasons for the loss of biodiversity and the decline in the quality of regional environments. On the local scale, urbanization is considered to be the greatest pressure on biodiversity [2,[5][6][7]. In most urban areas, biodiversity is maintained only within a small portion of the isolated and discontinuous vegetation patches that were set aside during the development of the areas [8].…”