On a Sex Difference in the Infection Rate of Birds with Syngamus trachea

Extract

In 1937 a short paragraph by Whitlock appeared in the Journal of Parasitology commenting on the fact that there appeared to be a sexual difference in the degree of infection with Syngamus trachea of some Hungarian partridges which were being confined at the Michigan State Game Farm. Of 34 infected birds that he examined, 32 were females. He puts forward the suggestion that the strain of egg laying had lowered the vitality of the females to such an extent as to allow of the establishment of the parasite. We must assume therefore that all these birds were fully adult and that they were examined in the spring or early summer.