POCHARD DE­CLINE IN­VES­TI­GA­TION

Bird Watching (UK) - - News Wire -

More preda­tors and less gulls are among the rea­sons be­ing sug­gested for the re­cent de­cline of Pochards. An in­ves­ti­ga­tion in the lat­est is­sue of Wild­fowl, the in­ter­na­tional sci­en­tific jour­nal of the Wild­fowl & Wet­lands Trust (WWT), looked at why the num­ber of Pochards mi­grat­ing to the UK for win­ter has de­creased by 60% since the 1980s, de­spite the num­ber that breed here dou­bling over the same pe­riod. This de­crease re­flects wide­spread de­clines in breeding num­bers recorded else­where across Europe. A pa­per by 29 re­searchers from across Europe says sev­eral changes are likely to have con­trib­uted to the Pochards’ de­cline. Firstly, the de­cline of Black-headed Gulls, whose colonies are used for pro­tec­tion by many other nest­ing birds, in­clud­ing Pochards, is sug­gested. An in­crease in the amount of nu­tri­ents washed off farm­land may also have played a part. They prompt ex­plo­sions of plants and al­gae in wet­lands and wa­ter­ways, pre­vent­ing Pochards from div­ing for food. Fi­nally, preda­tors may be in­volved. Mink, es­caped from fur farms, plus in­tro­duced Rac­coons and Rac­coon Dogs, have be­come ma­jor wetland hunters. Wild­fowl Ed­i­tor and WWT Re­search Fel­low Dr Eileen Rees said: “Wa­ter­birds live com­plex lives and their wetland habi­tats are en­twined with our own need for food and wa­ter. Water­bird pop­u­la­tions are of­ten spread across na­tions and con­ti­nents, and they’re highly mo­bile, breeding, stag­ing and win­ter­ing in dif­fer­ent places.”

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