Show keeping U p wi C ciance i e n e ell mer n ervi e 0 science service service crows are enemies of the wild duck s in in breeding season control methods are recommended by expert washington crows are major enemies of wild ducks in at least a part of the great wild duck breeding grounds in canada a survey by E R kalmbach 0 of f the united unite d states biological survey shows of duck nests studied 31 per cent nests had been ravaged by crows other causes of destruction had accounted for another 20 per cent of loss so that of all the nests that started the season with hopeful batches of eggs only 49 per cent turned out live ducklings duc klings it is possible however mr kalmbach notes that part of the egg destruction by crows might have been wreaked wrecked after the parent ducks had abandoned the nests for other causes furthermore he cautions this survey was made in a part of the nesting area where the crow concentration cent ration Is unusually high and where a large duck population offers unusually great temptation to raid for eggs the overlap of crow range and duck nesting arez area does not represent more than about a sixth of the whole productive waterfowl w ater nesting area in alaska and canada so crows cannot be counted universal enemies of ducks now how they should be controlled for practical control purposes mr kalmbach recommends crow control operations on duck breeding grounds should by all means be entrusted only to those who fully recognize the hazards associated socia ted with human intrusion on waterfowl nesting grounds at winter crow roosts boosts where control is possible at a lower cost per bird the benefits with respect to waterfowl are in turn less direct since only a part of the birds present at these roosts boosts actually enter the problem of crow waterfowl relationships on the breeding grounds for the present and probably for years to come such control may wisely be restricted to those f federal era state or privately managed areas to which crows have been attracted in unduly large numbers by the presence of nesting waterfowl and on which the consequently delicate problem of control may be kept in experienced hands hand |