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Contrasting the suitability of shade coffee agriculture and native forest as overwinter habitat for Canada Warbler (Cardellina canadensis) in the Colombian Andes.

Citation

Gonzalez, Ana M.; Wilson, Scott; Bayly, Nicholas J.; Hobson, Keith A. (2020), Contrasting the suitability of shade coffee agriculture and native forest as overwinter habitat for Canada Warbler (Cardellina canadensis) in the Colombian Andes., Dryad, Dataset, https://doi.org/10.5061/dryad.7sqv9s4pk

Abstract

In the Neotropics, coffee production occurs on a large scale in some of the planet’s most biodiverse regions: tropical mountains. Coffee production systems involving shade trees are considered to have a lower impact on biodiversity than alternative sun coffee. To date, the majority of evidence for the value of shade coffee plantations has not taken into account the relative quality of this habitat compared to the native forests they replaced. We determined the suitability of shade coffee and forest as winter habitat for Canada Warbler (Cardellina canadensis) by comparing variation in the likelihood of capturing individuals, seasonal changes in body condition, and estimates of annual survival between the two habitats. We also determined the effect of the strong 2015-2016 El Niño event on survival. Males were relatively more likely to be captured in forest than females and this likelihood increased during drier years. Body condition change over the winter and apparent annual survival were very similar for individuals that used forest and coffee. However, condition and survival decreased in both habitats during the El Niño year. Apparent survival was also lower for individuals carrying a radiotag or geolocator. Our findings suggest that shade coffee with high canopy cover and height offers similar benefits to forest in terms of body condition and survival. Landscape conservation approaches, promoting diverse matrices of structurally complex shade coffee and forest might best ensure long-term survival in Neotropical migrants like Canada Warbler.

Methods

Data were collected from December to March over five field seasons  (2013-2014, 2014-2015, 2015-2016, 2016-2017, and 2017-2018) in three study sites located on the western slope of the Eastern Andes in Colombia: “Hacienda La Fragua” (shade coffee 1400 m asl, forest 1500 m asl), “Los Vientos” (shade coffee and forest 1350 m asl); and “La Vuelta” (shade coffee 1400, forest 1700 m asl). 

We carried out constant-effort mist netting at fixed banding stations from 1 December to 30 March during eight days a month in each habitat. Weather permitting, 12-15 mist nets (30 mm mesh) were operated from 06:00 to 11:00 h and from 15:00 to 17:30 h. All captured birds were fitted with a U.S. Fish and Wildlife Service numbered aluminium band and processed and released at the capture site. We determined age and sex, and recorded body mass (±0.1 g, using an electronic balance) for each bird at first capture and for all birds recaptured.