Comparison of foraging behaviour of small, urban-sensitive insectivores in continuous woodland and woodland remnants in a suburban landscape

Abstract

Small patches of remnant vegetation are often considered to have low conservation value. In urban landscapes their value may potentially be higher than in other landscapes because they can be the only representatives of original native vegetation. Despite this potential, many small insectivorous birds that rely on native vegetation demonstrate sensitivities within urban landscapes through reduced numbers or total absence. One reason for this sensitivity may be that remnants are of suboptimal quality, which may be reflected in behavioural changes. Using five insectivorous species that were present (in low numbers) in remnants surrounded by high-density housing, foraging behaviour was examined in relation to vegetation. The proportion of time birds spent on different foraging substrates and plant species was compared with that of conspecifics in continuous vegetation. Canopy and shrub foragers showed minimal behavioural changes. Ground foragers in remnants tended to forage at lower heights than those in continuous vegetation; however, these changes did not appear to reflect a negative effect. These changes were partially explained by structural differences between vegetation in remnants and continuous sites. The number of times a bird attacked prey items was significantly higher in continuous habitat for only two species. Overall, the foraging behaviour of small insectivorous birds in remnants surrounded by high-density housing was not adversely affected by urbanisation and it appears that remnants have potential value as habitat and foraging sources in an urban landscape. Despite this, small insectivores are still sensitive to urbanisation, suggesting that other factors, probably in the matrix, are important.

Environmental and socio‐economic factors related to urban bird communities

“…While local-scale factors are important, landscape characteristics at larger scales may also influence the structure and dynamics of fauna communities, particularly for highly mobile species (Chamberlain et al 2004;Warren et al 2008;Oneal & Rotenberry 2009). A single household garden is unlikely to provide all the resources required for most vertebrates and the influence of landscape characteristics such as remnant native vegetation cover and riparian areas should be considered (Hennings & Edge 2003;Hodgson et al 2006;Pennington et al 2008). Indeed, studies of urban bird communities in Australia that confine their surveys to remnant vegetation patches within urban areas generally find that larger remnants support more species (e.g.…”

Exotic trees can sustain native birds in urban woodlands

“…Native plants may provide a more valuable and abundant source of food than similar exotic species for suburban nectarivorous and insectivorous birds (Beissinger and Osborne 1982;French et al 2005;White et al 2005;Hodgson et al 2006;Mackenzie et al 2014). Native insectivores, nectarivores and frugivores are all more likely to be adversely affected by urbanisation than omnivores and granivores due to limited food availability as a result of the replacement of native with exotic vegetation (Lim and Sodhi 2004;White et al 2005;Corlett 2005), with insectivorous birds being particularly vulnerable (Beissinger and Osborne 1982;Lim and Sodhi 2004;White et al 2005;Hodgson et al 2006).…”

The response of ground and bark foraging insectivorous birds across an urban–forest gradient

“…The target species are the eastern yellow robin (Eosaltrica australis), superb fairy wren (Malurus cyaneus), white-browed scrubwren (Sericornis frontalis) and the white throated treecreeper (Cormobates leucophaeus). These species forage primarily on or near the ground (Ambrose and Davies, 1989;Cale, 1994;Hodgson et al, 2006) with the exception of the white throated treecreeper which is a bark and trunk forager (Lindenmayer et al, 2007). They are also considered forest dependant species that are unable to utilize the streetscape component of urban environments (White et al, 2005).…”