Urban green space management for invertebrates and house sparrows

• Main Author: Weir, Jacqueline Elizabeth Sara
• Format: Dissertation
• Language: English
• Published: Imperial College London 2015
• DOI: 10.25560/28960

Urban house sparrow nestlings can develop poorly through lack of invertebrate food (Peach et al., 2008). Productivity can be increased by providing invertebrates (Peach, Sheehan & Kirby, 2014; Peach et al. in press). This study tested the effectiveness of three habitat treatments in increasing invertebrates and seeds in London parks, and their usage by house sparrows. Treatments were: annually sown ‘wildlife seed’ plots; sown perennial wildflower meadows; and existing grass grown taller. Treatment establishment and seed abundance were assessed by vegetation measurements, and practicality qualitatively assessed through questionnaires. Invertebrate abundance and variety were measured using sweep netting and vacuum sampling, and relationships tested with treatment type and modelled air pollution levels. Bird usage, and local house sparrow populations and productivity, were monitored over three years and relationships tested with treatments and air pollution. All treatments provided more invertebrates and seed than short grass. Wildlife seed plots contained the most seed during both autumn and winter. Wildflower meadows supported the most invertebrates, while each treatment benefited particular groups. Invertebrate variety at family level was highest in wildflower meadows and wildlife seed plots, probably through increased plant diversity. Abundance for numerous groups related positively to sward height. Varied vegetation structure should benefit the most invertebrate groups. Wildlife seed plots were most used by house sparrows, largely in the breeding season for invertebrates, while wildflower meadows were not used. Open vegetation structure probably permitted birds access. Wildlife seed plots may have buffered colonies against breeding season food shortages in one year. No strong relationships were found between invertebrate abundance and air pollution. Relationships between house sparrow population parameters and air pollution were mixed. Heterogeneous vegetation structure is important for invertebrates, and for bird access to food. Habitat homogenisation at various scales, combined with other pressures, may contribute to limiting urban house sparrow populations.