The more things change: species losses detected in Phoenix despite stability in bird–socioeconomic relationships

The science of urban ecology has increasingly grappled with the long-term ramifications of a globally urbanized planet and the impacts on biodiversity. Some researchers have suggested that places with high species diversity in cities simply reflect an extinction debt of populations that are doomed to extinction but have not yet disappeared. The longitudinal studies conducted to date have found species composition shifting with urbanization but have not always documented continued species extirpations post-urbanization. We used long-term monitoring data on birds from the greater metropolitan area of Phoenix, Arizona, to measure changes in residential bird communities, species–habitat relationships, and human perceptions of bird species diversity over a five-year period. Bird richness, occupancy, and abundance decreased, as did the percentage of respondents satisfied with bird variety in their neighborhoods. As in previous analyses for this region, we found that desert specialist species were associated with neighborhoods with xeric landscaping consisting of gravel groundcover, and drought-tolerant, desert-adapted vegetation. These species were also found in neighborhoods with high per capita income rates and lower percentages of renters and Hispanic/Latinx residents. Non-native species were positively associated with neighborhoods containing mesic yards with grass and other water-intensive vegetation. The proportions of yards in our surveyed neighborhoods with these distinct landscaping types likewise remained relatively stable over five-year period. Although habitat–species relationships remained unchanged, we detected significant loss of species across the sampling period. Declines were not confined to desert specialist species but included generalist and invader species as well. The parallel reduction in residents’ satisfaction suggests that people perceive some aspect of this environmental degradation. Further investigation into the mechanisms underlying these species losses may reveal options for retaining some desert specialist species, and the uniqueness they contribute to urban fauna.