Are ecosystem engineers keystone habitat providers for secondary cavity nesters in temperate forests of South America?
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Date
2021
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Abstract
Ecosystem engineers influence resource availability for other organisms, and thus they play important roles as drivers of community assembly. We investigated the relationship between nest occurrence of secondary cavity nesters (SCNs: Thorn-tailed rayadito, Chilean swallow, and Southern house wren) and their selection of cavities supplied by five ecosystem engineers (Magellanic woodpecker, Chilean flicker, Striped woodpecker, White-throated treerunner and rot fungi/insects) in a Global Biodiversity Hotspot, southern Chile. Further, we quantified the reproductive success of SCNs as a function of the characteristics of cavities (internal volume, entrance size and height) supplied by ecosystem engineers. We searched for nests during 10 breeding seasons and monitored each nest to determine cavity origin, nest fate and quantified cavity characteristics. We found 842 nests for our three SCNs. Most nests (>80%) of rayaditos and house wrens were placed in cavities supplied by Rot fungi/insects with relatively small volumes (1976 ± 121.7 and 1857 ± 185.6 cm3 , respectively) but with different entrance sizes and heights. Swallow nests were placed in high cavities (8.2 ± 0.42 m)with small-sized entrances (3.4 ± 0.11 cm), and chiefly supplied by White-throated treerunners (56%). Reproductive success of SCNs varied between 50-65%, but the cavity characteristics showed no influence on the reproductive success of any species. Rot fungi/insects play a major role as ecosystem engineers for SCNs, however some ecosystem engineers may be functionally similar. The conservation of populations of SCNs may require the development of different management actions for each key ecosystem engineer in temperate forest of South America.
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Ornithology, Temperate forests, Keystone species, Neotropical ornithology