Does Restored Riparian Habitat Create Ecological Traps for Riparian Birds Through Increased Brown-Headed Cowbird Nest Parasitism?

Abstract

A growing concern among restoration ecologists is inadvertently creating ecological traps, yet identifying ecological traps is difficult, particularly over a large region and for an entire suite of species. Here we use an example to show that restoration ecologists can evaluate the risk of creating ecological traps. We reviewed the literature and synthesized data to evaluate the risk that restored riparian forests create ecological traps for riparian birds by attracting dense populations of the brood parasite, Brown-headed Cowbird (Molothrus ater; hereafter cowbird) in the Central Valley of California, U.S. We found that most riparian bird populations are not highly vulnerable to cowbird parasitism, that there were no differences in cowbird density or parasitism rates between restored and remnant riparian forests, and that the riparian bird community responded positively to restoration. We concluded that riparian restoration in California's Central Valley has a low risk of creating ecological traps through cowbird parasitism. We recommend that restoration ecologists consider the potential for creating an ecological trap early and throughout the restoration design and implementation process, and include plans to monitor species responses to restoration, both in restored areas and in source populations nearby, as well as any specific conditions associated with a potential trap.

Increased abundance and productivity of a grassland bird after experimental control of invasive tall fescue

“…However, there is an urgent need to assess the potential for short‐term negative impacts of herbicide (Sullivan & Sullivan 2003; Johnson et al 2011; Lindenmayer et al 2017), especially for rapidly declining grassland bird species. Although previous studies show that bird abundance increases after restoration of invaded grasslands (Osborne & Sparling 2013), restoration activities may still create ecological traps (Dybala et al 2014), especially in the short term as native vegetation recovers after herbicide or seeding treatments. Despite these urgent research needs, few experiments exist, and fewer are conducted at scales broad enough to be relevant to avian territories (but see Rivers et al 2019).…”

Ecological spillover dynamics of organisms from urban to natural landscapes

“…We found three papers that address urban to wildland spillover effects within the context of ecological traps (Leston and Rodewald 2006;Mannan, Steidl and Boal 2008;Dybala et al 2014). Ecological traps describe habitats within a heterogeneous habitat matrix that have lower fitness for focal species despite having similar per capita resources when compared with similar habitats (Robertson and Hutto 2006).…”

“…Each of the papers we found examined the potential for urban areas to function as traps for the larger surrounding wildland matrix. Two of the studies directly tested ecological trap dynamics (Leston and Rodewald 2006;Mannan et al 2008), and one was a literature review and data synthesis paper (Dybala et al 2014).…”

“…We also searched the same term clusters on Google Scholar to allow for a search of the broadest selection of Ecological spillover dynamics of organisms from urban to natural landscapes | 3 peer-reviewed journals available. We found only one relevant paper (Dybala et al 2014) from peer-reviewed journal Ecological Restoration which is not included in Web of Science BIOSIS database.…”

Getting Our Heads Above Water: Integrating Bird Conservation in Planning, Science, and Restoration for a More Resilient Sacramento–San Joaquin Delta

“…Synthesize existing information on restoration and land-management outcomes within the Delta and Central Valley, to inform multiple-benefit project design and adaptive management efforts within the Delta. These should include indicators of ecological function, wildlife responses to restoration, other potential co-benefits and trade-offs to human communities, and the potential effects of non-native species on success (e.g., Dybala et al 2014Dybala et al , 2019bGardali et al 2006;Underwood et al 2017).…”