Nests in the cities: adaptive and non-adaptive phenotypic plasticity and convergence in an urban bird

Abstract

Phenotypic plasticity plays a critical role in adaptation to novel environments. Behavioural plasticity enables more rapid responses to unfamiliar conditions than evolution by natural selection. Urban ecosystems are one such novel environment in which behavioural plasticity has been documented. However, whether such plasticity is adaptive, and if plasticity is convergent among urban populations, is poorly understood. We studied the nesting biology of an ‘urban-adapter’ species, the dark-eyed junco ( Junco hyemalis ), to understand the role of plasticity in adapting to city life. We examined (i) whether novel nesting behaviours are adaptive, (ii) whether pairs modify nest characteristics in response to prior outcomes, and (iii) whether two urban populations exhibit similar nesting behaviour. We monitored 170 junco nests in urban Los Angeles and compared our results with prior research on 579 nests from urban San Diego. We found that nests placed in ecologically novel locations (off-ground and on artificial surfaces) increased fitness, and that pairs practiced informed re-nesting in site selection. The Los Angeles population more frequently nested off-ground than the San Diego population and exhibited a higher success rate. Our findings suggest that plasticity facilitates adaptation to urban environments, and that the drivers behind novel nesting behaviours are complex and multifaceted.

Mottled Duck introductions to South Carolina: The ugly, the bad, and the good?

“…Genetic components of animal personalities can influence resource use of individuals (Miranda et al, 2013 ; Schielzeth et al, 2011 ; Van Oers et al, 2004 ). Cities are evolutionarily novel environments with unfamiliar challenges for wildlife, and urban landscapes are thus ideal systems for understanding how plasticity might promote or hinder adaptation to new environments (Bressler et al, 2020 ; Shanahan et al, 2013 ; Sol et al, 2013 ). In dark‐eyed juncos ( Junco hyemalis ) and Eurasian magpies ( Pica pica ), both demonstrated a protracted breeding season in urban areas, possibly resulting from milder climates or greater food abundances compared with their conspecifics in natural habitats (Bressler et al, 2020 ; Jerzak, 2001 ).…”

“…Cities are evolutionarily novel environments with unfamiliar challenges for wildlife, and urban landscapes are thus ideal systems for understanding how plasticity might promote or hinder adaptation to new environments (Bressler et al, 2020 ; Shanahan et al, 2013 ; Sol et al, 2013 ). In dark‐eyed juncos ( Junco hyemalis ) and Eurasian magpies ( Pica pica ), both demonstrated a protracted breeding season in urban areas, possibly resulting from milder climates or greater food abundances compared with their conspecifics in natural habitats (Bressler et al, 2020 ; Jerzak, 2001 ). What remains equivocal for birds generally is whether plasticity is adaptive for urban populations relative to fitness outcomes, and whether urban systems might selectively filter out individuals or species that either do not exhibit behavioral plasticity or show maladaptive plasticity in their new environment (Aronson et al, 2016 ; Bressler et al, 2020 ).…”

“…In dark‐eyed juncos ( Junco hyemalis ) and Eurasian magpies ( Pica pica ), both demonstrated a protracted breeding season in urban areas, possibly resulting from milder climates or greater food abundances compared with their conspecifics in natural habitats (Bressler et al, 2020 ; Jerzak, 2001 ). What remains equivocal for birds generally is whether plasticity is adaptive for urban populations relative to fitness outcomes, and whether urban systems might selectively filter out individuals or species that either do not exhibit behavioral plasticity or show maladaptive plasticity in their new environment (Aronson et al, 2016 ; Bressler et al, 2020 ). Human urbanization in parts of Florida is already population dense and increasing, and SACZ Mottled Ducks would seemingly encounter novel environments in suburban and urban areas already occupied by Florida Mottled Ducks (Bielefeld & Cox, 2006 ).…”

“…Genetic components of animal personalities can influence resource use of individuals (Miranda et al, 2013;Schielzeth et al, 2011;Van Oers et al, 2004). Cities are evolutionarily novel environments with unfamiliar challenges for wildlife, and urban landscapes are thus ideal systems for understanding how plasticity might promote or hinder adaptation to new environments (Bressler et al, 2020;Shanahan et al, 2013;Sol et al, 2013). In dark-eyed juncos (Junco hyemalis) and…”

The Decline, Fall, and Rise of a Large Urban Colonising Bird

“…Their ground nesting, lack of parental care, and poor ight abilities contrast with the off-ground nesting and high dispersal ability (through ight) common to most successful urban birds (seeBressler et al, 2020; …”