DOI: 10.5061/dryad.dz08kps35
title: Data from: Identifying links between the biodiversity impacts and monetary costs of alien birds

description: This dataset accompanies a published paper (Evans et al. 2023) which aims
 to identify links between the biodiversity impacts and monetary costs of
 alien bird species. In this paper we used mixed-effects models to test:
 (1) whether alien bird species with severe biodiversity impacts also had
 high monetary costs; (2) whether specific types of biodiversity impacts
 were associated with high monetary costs; and (3) whether certain factors
 caused alien bird species to have both severe biodiversity impacts and
 high monetary costs. This dataset includes all data used for the analysis,
 including biodiversity impact scores and monetary costs for each alien
 bird species, and the variables tested for their influence on these
 biodiversity impacts and costs. Please refer to Evans et al. (2023) for
 details on the methods used. The abstract to the published paper follows.
 Alien species can be damaging to native biodiversity, human well-being and
 the economy. Identifying the complete range of impacts they cause, and the
 ways that these impacts are connected, may inform the prioritisation of
 management actions to mitigate impacts. Using datasets on the biodiversity
 impacts and monetary costs (damage and management costs) of alien birds,
 we aimed to establish whether species with the most severe biodiversity
 impacts also had the highest costs; whether types of biodiversity impact
 were associated with high costs; and whether specific factors associated
 with alien species are linked to both damaging biodiversity impacts and
 high costs. We identified a positive relationship between a specific type
 of biodiversity impact (predation) and costs, possibly because predation
 by alien birds can be severely damaging to native species and therefore
 attracts management actions. However, predation impacts are likely to
 occur more frequently and to be easier to identify than some other impact
 mechanisms such as hybridisation and transmission of diseases, and they
 are therefore likely to be more frequently managed, and hence to have
 costs. We identified a specific species characteristic (generalism) to be
 associated with severe biodiversity impacts and high costs, probably
 because generalist species have greater opportunity to cause impacts,
 whether they be on biodiversity or the economy, or both. We also found
 widely distributed alien birds to be associated with high costs, probably
 also because these species have greater opportunity to cause impacts.
 Management interventions that prevent the introduction of both predatory
 and generalist alien bird species, or that reduce their geographic
 distribution at early stages of invasions, may have significant
 biodiversity and economic benefits.
description: Please refer to the published paper associated with this dataset,
 which provides a detailed description of the data collection
 methods.
description: <strong>Variable</strong> <strong>Description</strong> Biodiversity impact A binary variable to measure the most severe reported impact to biodiversity caused by an alien bird species (0 = less severe; 1 = more severe). Monetary cost The total reported monetary costs caused by an alien bird species. Competition Whether a species has reported competition impacts. Predation Whether a species has reported predation impacts. Other mechanisms Whether a species has reported impacts through impact mechanims other than competition and predation. These mechanisms include hybridisation, grazing, disease transmission, parasiism and structural impacts on ecosystems. V1: Body mass Average adult body mass (g). V2: Sociality The degree of sociality associated with a species: (i) solitary; (ii) small flocks/parties; (iii) medium flocks/parties; (iv) large flocks/parties and large communal roosts. V3: Habitat breadth The number of major habitat types that an alien bird species may occupy in its native range (maximum number of habitat types = ten). Habitat types: marine habitats, including littoral rock and sediment; coastal habitats; inland surface waters; mires, bogs, and fens; grasslands and lands dominated by forbs, mosses or lichens; heathland, scrub, and tundra; woodland, forest, and other wooded land; inland unvegetated or sparsely vegetated habitats; regularly or recently cultivated agricultural, horticultural, and domestic habitats; constructed, industrial, and other artificial habitats. V4: Diet breadth The number of major food types consumed by an alien bird species (maximum number of food types = eight). Food types: grasses/forbs; seeds/grains; fruits/berries; pollen/nectar/flowers; tree leaves/branches/bark; roots/tubers; invertebrate prey; vertebrate prey/carrion. V5: Native range size The size of a bird species’ native breeding range (km<sup>2</sup>). V6: The proportion of a species’ diet comprising animal matter The proportion of an alien bird species’ diet comprising animal matter (calculated using proportional data on the types of food consumed by each species). V7: The proportion of a species’ diet comprising seeds and fruit The proportion of an alien bird species’ diet comprising seeds and fruit (calculated using proportional data on the types of food consumed by each species). V8: Alien residence time The number of years that have passed since an alien bird species was first introduced. V9: Alien range size The size of a bird species’ alien range (km<sup>2</sup>). V10: Relative brain size Average adult brain size relative to its body mass.