Swartz, T. M. | Search bioRxiv

bioRxiv2026

Advancement of spring arrival and delayed autumn departure in Ruby-throated Hummingbird (Archilochus colubris) migration phenology over more than a century

Climate change is thought to have altered the timing of avian migration, with species-specific responses varying across spatial and temporal scales. This is notable as ecological mismatches may occur when birds arrive or depart out of sync with the peak flowering period of their associated food plant resources. This study compares first arrival and last departure dates of Archilochus colubris (Ruby-throated Hummingbird) using citizen science data from the North American Bird Phenology Program for historical records (1880-1969) and recent records from eBird (2006-2024) and Journey North (2001-2024). Results show significantly earlier spring arrivals (14.2-27.9 days) and later fall departures (17.3-33.7 days) in the recent period compared to historical periods, while migration pace remained relatively consistent across datasets. Although temperatures are increasing in both the nonbreeding and breeding ranges of A. colubris, winter and fall temperatures were not strong independent predictors of migration timing. This study is the first to document shifts in fall departure dates for the species and highlights the need for continued research to uncover the mechanisms driving these phenological changes and assess their broader ecological implications.

ecology↗

bioRxiv2022

A functional trait approach reveals the effects of landscape context on ecosystem services provided by urban birds

Land use intensification in urban areas can have profound effects on biological communities that provide valuable ecosystem services to urban residents. We used a functional response and effect trait approach to determine how bird species responses to local and landscape-scale habitat of urban green spaces affects the supply of cultural and regulating ecosystem services. We sampled bird communities and habitat variables in urban green spaces that varied in local and landscape-scale habitat composition and compiled a dataset of species response and effect traits related to nesting, foraging, diet, and visual and acoustic aesthetic appeal. Overall, the landscape-scale context of a green space had a stronger influence on species abundances than local-scale habitat. Landscape-scale impervious surface surrounding our study sites interacted with response traits related to nesting in human-built structures, clutch size, and consumption of invertebrates to drive bird species abundances. Because correlations between response and effect traits can influence the effect traits available to provide ecosystem services at a site, we explored the correlation of these three response traits to a suite of effect traits and found the response traits were correlated with several effect traits related to diet and regulating services but correlated with few of the plumage and acoustic traits that produce cultural services. Finally, we found that effect traits associated with cultural and regulating ecosystem services varied strongly along the landscape-scale gradient of urbanization. Sites with high impervious surface cover are expected to have low levels of invertebrate pest control and visual appeal but high levels of acoustic appeal, diet evenness (generalism), and granivory. Overall, our study highlights the key role of landscape-scale habitat in driving bird-mediated ecosystem services and underscores the importance of regional urban planning to create healthy and livable cities.

ecology↗