Avian diversity above the clouds: comparing elevational patterns in north and south temperate mountains
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Date
2018
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Abstract
Mountain ecosystems comprise 24% of the land-base of the Americas, and are critical components of the life-cycle for 35% of North American bird species. Globally, however, high elevation avian communities are poorly monitored, with taxonomic and functional diversity receiving little attention. In 2017, we initiated a temperate montane bird study, comparing: i) taxonomic and functional turnover across three habitats increasing in elevation: upper montane (>50% tree cover), subalpine (5-50% tree cover), and alpine (<5% tree cover), and ii) the breeding strategies of alpine birds in North and South America. We conducted 600 diurnal bird point counts in six North temperate (British Columbia, Canada; 54°N latitude) and 10 South temperate mountains (Chile; 39°S latitude). Species richness was comparable between sites (49-54 species), but decreased with elevation in Canada (upper montane: 31, alpine: 16) compared to remaining consistent across elevation in the Chilean Andes (~33 in each habitat). Species composition among mountains was highly variable in both hemispheres (Jaccard index < 0.5) indicating potential variation in drivers such as habitat structure. We found contrasting patterns in alpine breeding strategies, as open-cup nesters made up 88% (14/16 species) of the Canadian alpine community, while 100% of the 37 nests (6 species) found in the Chilean alpine were cavity nesters (rock crevices or ground excavations). Comparing high elevation temperate ecosystems in the Americas provides a strong framework to address avian breeding dynamics in stochastic environments, as well as understand the potential conservation value of mountain habitats as refugia for avian populations with environmental change
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Keywords
Botany, Ornithology, Conservation biology, Ecology, Andes, Functional diversity