DOI: 10.5061/dryad.573n5tbht
title: Large invasive herbaceous plants decrease the taxonomic, functional and phylogenetic diversity of birds via their reproductive traits

description: Birds are among the organisms most impacted by plant invasions, the
 effects of which are particularly conspicuous during the breeding season.
 Birds can incorrectly assess the suitability of large, invasive hogweeds
 Heracleum sp. in south-eastern Poland when selecting nesting sites early
 in spring when the developing invaders do not yet differ substantially in
 form from the rest of the vegetation. One would expect lower bird breeding
 success in areas with invasive hogweeds. Furthermore, this may shift bird
 community composition towards species with filtered traits, which may then
 be reflected in various measures of diversity. To assess these
 expectations, we conducted bird surveys at 74 sites, arranged as 37 pairs
 (with invasive Heracleum vs. control). The presence of Heracleum was
 associated with lower bird taxonomic and phylogenetic diversity.
 Functional richness (calculated based on species' reproductive
 traits) was also lower at sites with these invaders. The species detected
 at Heracleum sites were characterised by traits associated with rapid
 breeding, e.g., small clutches, short incubation periods, and short
 fledging periods. We show that the bird community at sites with hogweeds
 became less diverse and composed of random species sharing similar
 reproductive traits. Bird communities with low diversity at Heracleum
 sites tended to exhibit a common trait syndrome. These patterns provide
 insights into the mechanisms of how invasive plants may lead to the loss
 of some traits and species in bird communities.
description: # Large invasive herbaceous plants decrease the taxonomic, functional and
 phylogenetic diversity of birds via their reproductive traits
 [https://doi.org/10.5061/dryad.573n5tbht](https://doi.org/10.5061/dryad.573n5tbht) ## Description of the data and file structure Birds are among the organisms most impacted by plant invasions. This research is based on the prediction that invasive hogweeds *Heracleum* sp. may act as a filter for specific reproductive traits. We investigated the invasion-altered assembling of species in a bird community and assessed the taxonomic, functional and phylogenetic diversity of birds. The research was conducted in south-eastern Poland, where 15 localities with abundant Caucasian hogweeds *Heracleum* sp. were selected. The 74 study sites for surveying birds were set within these localities. Each study site consisted of a circle with a centre point and a radius of 100 m (i.e., covering 3.14 ha). While 37 of the study sites contained no invasive *Heracleum*, the remainder had various levels of infestation. Bird communities were investigated at these 37 pairs of surveying points. Surveys were conducted five times at 64 study sites and four times at the other 10 sites, during 2020–2021. This represents a total of 360 field surveys at 74 sites. During the surveys, all birds were recorded if they were seen or heard within a radius of 100 m, for a minimum of 10 minutes between sunrise and 11 a.m. After this, the observer approached the edge of the 100 m circle and performed supplementary counting for another 10 min.  The community data prepared for the analysis included maximum bird species abundances per site from all surveys on the 74 sites. However, research on the breeding activity of individual birds is not feasible in patches with invasive *Heracleum* due to human health risks. We, therefore, relied on a set of characteristic reproductive traits for each species to describe the birds’ reproductive strategies and diversity. ### Files and variables #### File: FE-2023-01235.xlsx **Description:** The three sheets in the Excel file contain 1. diversity variables (described in "Variables") and mean abundance-weighted reproductive traits per site (described in "Reproductive traits"); 2. bird survey results from sites; 3. a list of bird names with abbreviations used in bird survey results heading. #### Variables * taxonomic diversity indices (Shannon's H diversity index, species richness, Pielou's evenness) were based on species abundances detected in the field at each site, * Faith's phylogenetic diversity was defined as the total branch length spanned by the tree that included all detected species in a community; it was calculated using the global phylogeny of birds on the birdtree.org website, including the 87 bird species detected in research, * functional diversity indices were calculated based on bird survey and their reproductive traits; they were as follows: functional richness (represents the possibility of expressing particular traits of a species in a community, and is a measure of the multivariate range of trait values), functional divergence (quantifies whether the abundant species are located towards the centre or the periphery of the trait spectrum occupied by the community), functional evenness (quantifies the regularity of species’ abundance distribution, allowing effective utilisation of the entire range of resources available). #### Reproductive traits * 10 reproductive traits for each bird species were as follows: minimum clutch size; mean clutch size; number of broods per year; nesting stratum (here, we used ordinal numeric values to reflect the vertical position and a gradually more closed nest type: 1 = open nest on the ground, 2 = closed nest on the ground, 3 = open-arboreal nest, 4 = closed-arboreal nest, 5 = cavity nest); incubation period (days); hatching asynchrony (1 = synchronous, 2 = asynchronous); nestling period (days); fledging period (days); age of offspring independence (days); migration distance (values reflecting a gradient from the most sedentary through intermediate to the farthest migrating birds: 1 = sedentary species, 2 = short-distance migrant, 3 = long-distance migrant), * the mean values of reproductive traits per site were calculated as a sum of trait values assigned to the species present on the site, multiplied by the number of birds representing a given species characterised by a set of traits, and divided by the number of birds recorded on the site. ## Code/software R 4.0.4 software R 4.0.4 packages used in analysis: bestNormalize, vegan, ggplot2, viridis, cowplot, fundiversity, glmmTMB, DHARMa. R 4.2.0 software R 4.2.0 packages used in analysis: picante, phytools, phangorn.