The effect of grass-endophyte associations on feeding of Canada geese (Branta canadensis)

Abstract

Canada geese (Branta canadensis) and other herbivorous birds (e.g. paradise ducks, pukeko) can be a significant problem for both pastoral farmers and recreational turf managers in a number of locations in New Zealand. Canada geese were offered seeds and herbage of selected ryegrass combinations of (Lolium perenne) and endophyte (Neotyphodium lolii) to examine the effects of endophyte and the associated alkaloids on feeding behaviour. Forty geese were captured annually during the moult in January and contained in fenced areas by wing clipping. In both choice and no-choice feeding trials, geese consumed up to four times more endophyte-free than endophyteinfected ryegrass herbage. In a seed feeding trial, the geese did not discriminate on first exposure between the endophyte-free seed and that containing endophyte. However on Day 2 there was an 80% rejection of the seed containing endophyte compared to the endophyte-fr ee seed. A similar rejection of 80% was observed after a three month endophyte-free feeding period, suggesting the rejection was a long term learned response involving post-digestion feedback. Grass/endophyte associations may add to the armoury of bird control methodology as a tool to manage birds using habitat modification. Keywords: alkaloids, Canada geese, endophyte, herbage, post-digestion seed