Are urban forests ecological traps for understory birds? An examination using Northern cardinals

Anthropogenic resource subsidies decouple predator–prey relationships

“…Moreover, because these species readily move between the urban matrix and forests (Oehler and Litvaitis 1996, Barratt 1997, Pedlar et al 1997, they can access a wide range of anthropogenic foods. Our previous research demonstrates that urban landscapes supply greater numbers of birdfeeders, abundant fruiting exotic plants, and residential and commercial buildings with trash receptacles (Borgmann and Rodewald 2005, Atchison and Rodewald 2006, Leston and Rodewald 2006.…”

“…Metropolitan areas are widely known to support greater densities and/or activity levels of many generalist and opportunistic predators (Crooks and Soule´1999, Sorace 2002, Gehrt 2004, Chace and Walsh 2006. Such positive responses of generalist predators to urbanization may stem from urban-associated changes in anthropogenic food resources as well as other ecological changes, such as the warmer winter temperatures and altered vegetation structure in urban forests in our system (Atchison andRodewald 2006, Leston andRodewald, in press). An important caveat is that, like most others, we may have poorly sampled nocturnal predators and our index of predator abundance reflects activity levels more than true densities.…”

Conserving Biodiversity in Urbanizing Areas: Nontraditional Views from a Bird's Perspective

“…While any of these individual factors has the potential to promote or discourage use of urban areas by particular species, multiple factors often act in concert. For example, the strong positive association observed between urbanization and numbers of an urban adapter, the northern cardinal (Cardinalis cardinalis), was likely a consequence of the fact that urban forests contained over twice as much fruit, birdfeeders, and preferred nesting substrate for cardinals than did rural forests (Leston and Rodewald 2006). Evidence of such resource-matching by urban adapters is further provided by Rodewald and Shustack (2008a), who showed that urban cardinals exhibited similar body condition and rates of survival and reproductive productivity to birds in more rural landscapes, despite maintaining up to four times higher population densities in urban than rural landscapes.…”

“…There also is evidence that exotic plants can alter species interactions at higher trophic levels, such as predator-prey relationships (Schmidt and Whelan 1999;Remes 2003;Borgmann and Rodewald 2004). In Ohio, for example, the exotic and invasive amur honeysuckle (Lonicera maackii) affected bird communities by providing the vast majority (>90%) of available fruits at sites during non-breeding seasons (Leston 2005), promoting a dense understory layer in riparian forests (Leston and Rodewald 2006), and inducing changes in nest placement (e.g., closer to the ground) in ways that increased the vulnerability of nests to predators (Schmidt and Whelan 1999;Borgmann and Rodewald 2004). Thus, maintaining a plant community comprised of native species may help to ameliorate some avian community responses to urbanization.…”

Earthworm, microbial biomass, and leaf litter decay responses after invasive honeysuckle shrub removal from urban woodlands.

“…14% chance of nest survival over 21 days); however, nest survival rates in honeysuckle patches rose throughout the season and eventually surpassed the nest survival rate in native substrates towards the end of the breeding season. Northern cardinals are known to preferentially nest in honeysuckle shrubs (Leston and Rodewald 2006) and pairs that first nested in L.…”