Do helminths increase the vulnerability of released pheasants to fox predation?

The success of ring-necked pheasant (Phasianus colchicus) restocking in Asturias, northern Spain was assessed, and the role of parasites and predators in the mortality of released birds was studied. The experimental release of 56 radio-tagged pheasants showed that 98% of birds died within 12 days. As soon as 72 h after release, 67.5% of males and 55.0% of females were found dead. Foxes (Vulpes vulpes) killed 63% of the birds. The survival of those birds killed by foxes was lower than for birds which died due to other causes, and pheasants depositing eggs of the nematode Eucoleus contortus (Creplin, 1839) survived less than those apparently non-parasitized. No impact of the parasite on the pheasants' condition was found, but foxes preyed upon parasitized birds more than expected by random. The results suggest that: (i) the current pheasant releases in this area are unsuccessful and need to be improved; (ii) this is mainly due to intense predation by red foxes; and (iii) parasites could have some influence on the predation of released birds by foxes. However, the way parasites affect pheasant vulnerability remains unclear.

Pathology of avian pox in wild red-legged partridges (Alectoris rufa) in Spain.

The diagnosis and pathology of an avian pox outbreak in free-living red-legged partridges in Cádiz, Southern Spain, is described. Diagnosis of the disease was based on histopathology, ultrastructural examination of, and virus isolation from lesions of necropsied animals. Lesions were present mainly in juvenile partridges (41%), and were observed primarily on the dorsal part of the digits or on the hock joint. The lesions ranged from small wartlike nodules to large tumor-like lesions. The presence of acute lesions of any grade as opposed to absence of lesions or healed lesions adversely affected body condition of the partridges (P <.01). Further investigations on the epidemiology of the disease and on the relation of the isolated strains to other avian poxviruses are under way.