Title

Preventing bird declines in urban landscapes: Influence of behavioural traits and streetscape plantings

Author Identifiers

Kaarissa Harring-Harris

https://orcid.org/0000-0002-5911-0875

Date of Award

2022

Degree Type

Thesis

Degree Name

Master of Science (Biological Sciences)

School

School of Science

First Advisor

Robert Davis

Second Advisor

Geoff Barret

Third Advisor

Tegan Douglas

Abstract

Urbanisation is thought to be the leading cause of habitat loss and ecosystem fragmentation world-wide. Australian urban bird communities are constantly under threat from landscape modification and the associated disturbances. The Perth metropolitan region, Western Australia provides a unique case study to observe the impact of a developing city that is also located in a biodiversity hotspot. The long-term reporting rate of 66 small passerine birds was analysed on a time and spatial scale, utilising 20 years of citizen science from Birdata collected by birdwatchers. The study compared the overall change in reporting rate to changes in the urban environment, focusing on human population density and the canopy cover of native trees. Life history traits were also used to determine if certain groups/guilds of birds responded differently to changes in the urban landscape.

This study revealed that a concerning number of urban sensitive native species are in decline and are being replaced by native and exotic ‘urban-exploiters’. Species that were found to be most at risk in this study were foraging specialists, particularly insectivores, small understorey-dependent birds, and species reliant on large bushland remnants. The study also found generalist species and large nectarivorous birds are increasingly dominating the urban community. Australian urban gardens and streets are lined with nectar-rich, seed-producing vegetation both native and exotic; therefore, favouring species that have the ability to exploit novel foraging resources. Significant loss of habitat in lower strata levels, as a result of land clearing, has reduced the connectivity between large bushland remnants. This has led to urban bird communities becoming overrun by species that frequently utilise the upper canopy and/or thrive in open green areas.

Many endemic and native species are locally threatened, and by identifying ‘at risk’ species we can better understand the association between environmental and ecological factors and the impact they have on an individual’s urban tolerance.

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