Fruit quantity of invasive shrubs predicts the abundance of common native avian frugivores in central Pennsylvania

Abstract

Aim Biological invasions pose one of the most severe threats to global biodiversity. Still, invasions can create positive ecological relationships and services, which can sometimes result in challenges for conservation efforts. A case in point is the invasion of alien plants that form mutualisms with native frugivorous birds. Here, we examined the correlation between honeysuckles (Lonicera spp.) and the bird communities in a landscape of central Pennsylvania during the fall months. Location State College area in central Pennsylvania, USA. Methods We conducted point counts to quantify the abundance of birds and fleshy‐fruited plant species within a 187.5 km2 landscape that included forested, urban and agricultural lands. We also compared fruit‐removal rates for a native fruiting plant under low and high Lonicera densities. Results The abundance of birds showed a strong positive association with Lonicera fruits, with the abundance of Turdus migratorius and Dumetella carolinensis showing the strongest correlations. We also found that fruit‐removal rates were 30% larger for a native plant species in areas of high Lonicera density compared to a site with low density of Lonicera. Main conclusions Our results suggest that Lonicera may currently serve as a main axis for the organization of bird communities and the networks of frugivore–plant interactions in central Pennsylvania. Since populations of key bird frugivores may be currently depending on Lonicera resources, we argue that control measures should account for the negative effects that the loss of this fruit resource could have on populations of native consumers in highly invaded regions.

Tradeoffs among Ecosystem Services Associated with Global Tilapia Introductions

“…While documented ecological changes were strongly associated with negative perspectives, this relationship was also dependent on the socioeconomic context, particularly the value of tilapia production and latent regional factors. These results are in agreement with previous work emphasizing that concepts of invasion are context specific and mutable (Lodge and Shrader-Frechette, 2003;Nuñez and Simberloff, 2005), and that complex perceptions are typical for introduced species that provide some ecosystem services while harming others (Davis et al, 2011;Gleditsch and Carlo, 2011;Schlaepfer et al, 2011). Some general considerations and potential analyses to further inform decision and policy making regarding tilapia introductions are discussed below.…”

“…The dissemination of aquatic species as a result of globalization has often had unexpected and harmful impacts on receiving ecosystems, human communities and economies (Lodge et al, 2006;Keller et al, 2009), though introduced species in some cases may provide significant benefits (Davis et al, 2011;Gleditsch and Carlo, 2011;Schlaepfer et al, 2011;Barnes et al, 2014). Global databases of introductions indicate relatively few negative impacts for many freshwater fish species particularly relative to the economic value of their production (Gozlan, 2008).…”

Effects of invasive shrub honeysuckle (Lonicera maackii) and forest composition on bird communities in woodland stands.

“…Gleditsch and Carlo (2011) examined how abundance of Lonicera fruit influences native frugivores in a large expanse of urban, forested, and agricultural landscape invaded by honeysuckle in central Pennsylvania. The Lonicera shrubs present in the study site varied from 0 to greater than 10,000 fruits per shrub.…”

“…With respect to other thrushes, wood thrushes were not found in the study area in the fall and other thrush species were relatively uncommon. The positive relationship between robin abundance and honeysuckle density in the fall is thought to be a consequence of plentiful honeysuckle berries, based on previous studies demonstrating an increase in robin abundance in response to increased fruit abundance (Gleditsch and Carlo 2011).…”

Plant ecology meets animal cognition: impacts of animal memory on seed dispersal

“…The vegetation of an area affects assemblages of seed dispersers, as the number of frugivore species and individuals is correlated with habitat structure and local abundance of fruit (Tellería and Pérez-Tris 2003;Tellería et al 2008;Gleditsch and Carlo 2011;Aparicio et al 2013). …”