Ecosystem engineers show variable impacts on habitat availability for cavity nesters in South American temperate forests

Ecosystem engineers are organisms that impact their environment and co-existing species by creating or modifying habitats, and thus they play important roles as drivers of community assembly. We examined whether cavity characteristics and/or habitat attributes associated with cavities provided by four ecosystem engineers, influence the presence of nests of three secondary cavity-nesting birds [Aphrastura spinicauda (Thorn-tailed Rayadito), Tachycineta leucopyga (Chilean Swallow), and Troglodytes aedon (Southern House Wren)], and whether these variations influence their reproductive success. We tested this by: i) assessing nest presence in cavities supplied by ecosystem engineers and ii) quantifying the reproductive success of secondary cavity nesters as a function of cavity characteristics and habitat attributes supplied by ecosystem engineers. Between 2009 and 2022, we recorded 757 cavities in 546 trees in old-growth and second-growth forests in a Global Biodiversity Hotspot in the And..., Study area and focal species
We conducted our study in Andean temperate rainforests of South America in the La Araucanía Region, Chile (39°16’S-71°48’W). The main weather characteristics of the area are cool summers and average annual precipitation >2000 mm distributed throughout the year. The surveyed sites included eight old-growth forests (>200 years) within public and private protected areas and seven second-growth forest sites (40-100 years) on private land (Ibarra et al. 2012, Caviedes and Ibarra 2017), each with a mean area of 40 ha (Fig. 1). Old-growth forest sites were mixed conifer-broadleaf forests dominated by Saxegothaea conspicua, Laureliopsis philippiana, and Nothofagus dombeyi (500-1000 masl) or by the conifer Araucaria araucana and Nothofagus pumilio (1000-1400 masl). Second-growth forest sites were dominated by broadleaf species including Nothofagus obliqua, N. dombeyi, and Laurelia sempervirens (Díaz et al. 2005, Altamirano et al. 2017). The understory in both o..., , # Ecosystem engineers show variable impacts on habitat availability for cavity nesters in South American temperate forests

[https://doi.org/10.5061/dryad.qjq2bvqqv](https://doi.org/10.5061/dryad.qjq2bvqqv)

## Description of the data and file structure

*Nest presence and cavity selection*

To assess the relationships between the nest presence of *A. spinicauda,* T. leucopyga, or *T. aedon* and the cavities supplied by ecosystem engineers, we first assigned a “1” to cavities with nest presence of any of these three secondary cavity nesters and “0” for cavities found empty or with the presence other nesting birds. For all analyses, we excluded years 2010 and 2022 because of a lack of data. We used generalized linear mixed models (GLMMs) with binomial error distributions and logit link functions. The identity of the ecosystem engineer, along with forest type (old-growth and second-growth forests), cavity volume (cm3), size of cavity entrance (cm), cavity height above ground (m), tree den...