Cryptic loss of montane avian richness and high community turnover over 100 years

• Published in: Ecology (Durham) Vol. 94; no. 3; pp. 598 - 609
• Main Authors: Tingley, Morgan W, Beissinger, Steven R
• Format: Journal Article
• Language: English
• Published: Washington, DC Ecological Society of America 01-03-2013
• Subjects: Altitude; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Applied ecology; Aves; Bayesian analysis; Biodiversity; Biological and medical sciences; Biological taxonomies; Birds; Birds - classification; Birds - physiology; California; Climate change; Climate models; Climatology. Bioclimatology. Climate change; Communities; detectability; Earth, ocean, space; Ecological modeling; Ecology; elevational gradient; environmental factors; Exact sciences and technology; External geophysics; Fundamental and applied biological sciences. Psychology; General aspects; hierarchical model; latitude; Meteorology; Models, Biological; Multilevel models; Population Dynamics; resurvey; richness loss; Sierra Nevada, California, USA; Species; species diversity; Synecology; turnover; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Sierra Nevada (California); United States; California; North America; America; USA, California, Sierra Nevada Mts; INE, USA, California; USA; elevational gradient; Loss; Detectability; richness loss; California; birds; Dynamical climatology; Climate change; Vertical gradient; Vertebrata; resurvey; Turnover; Sierra Nevada; Models; hierarchical model; Aves
• ISSN: 0012-9658; 1939-9170
• DOI: 10.1890/12-0928.1

Although there are numerous examples of individual species moving up in elevation and poleward in latitude in response to 20th century climate change, how communities have responded is less well understood and requires fully accounting for changes in species-specific detectability over time, which has been neglected in past studies. We use a hierarchical Bayesian occupancy model to examine bird species richness change and turnover along three elevation gradients surveyed 80-100 years apart in the Sierra Nevada of California, USA. Richness declined over the 20th century across all elevations. Turnover was greatest at the highest and the lowest elevations. These findings were only apparent, however, after species' detectability was incorporated into measures of species richness. Further partitioning of species richness changes by elevational life zone showed that numbers of low- and high-elevation species declined, without a concurrent expansion by mid-elevation species. Our results provide empirical evidence for biodiversity loss in protected montane areas during the 20th century and highlight the importance of accounting for detectability in comparisons of species richness over time.