Ecological Archives A023-010-A2

Sébastien Rioux Paquette, Dany Garant, Fanie Pelletier, Marc Bélisle. 2013. Seasonal patterns in Tree Swallow prey (Diptera) abundance are affected by agricultural intensification. Ecological Applications 23:122–133.

Appendix B (Fig. B1). Preliminary analysis of the diet of Tree Swallow nestlings in a system of nest boxes located in southeastern Quebec, Canada, from collected boluses.

In order to analyse the diet of Tree Swallow nestlings in our study system, we placed collars on nestlings (age between 3 and 14 days old) for a period of 60 min (two consecutive periods of 30 min). This approach is regarded as more efficient and less disruptive for nestlings than other methods employed to analyze chick diet (Blancher et al. 1987). Collars were made of an elastic band placed around the throat of nestlings and securely maintained with a 3-mm section of latex number 8 French feeding tube (Benlan, Oakville, Canada) as described in Smits et al. (2005). Tightening the elastic band prevented nestlings from swallowing a bolus while allowing them to breathe normally. Boluses were collected after each half-four period (i.e. after 30 and 60 min). Fifty-four half-hour periods were performed, allowing for the collection of 108 boluses from 14 June to 18 July 2007. Sampled nestlings were distributed among 32 clutches from 22 farms. Boluses were preserved in 90% ethanol. Insects in each bolus were identified to the order, and dry biomass was obtained after drying for 24 h in a dessication oven at 50 °C. In total, 3090 insects were collected and identified this way. The taxonomic distribution of insects found in boluses is illustrated below.



Literature Cited

Blancher, P. J., C. L. Furlonger, and D. K. McNicol. 1987. Diet of tree swallows (Tachycineta bicolor) near Sudburry. Ontario, summer 1986. Technical Report Series no. 31. O. R. Canadian Wildlife Service 1–14.

Smits, J. E. G., G. R. Bortolotti, M. Sebastian, and J. J. H. Ciborowski. 2005. Spatial, temporal, and dietary determinants of organic contaminants in nestling tree swallows in Point Pelee National Park, Ontario, Canada. Environmental Toxicology and Chemistry 24:3159–3165.

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