Microparasite assemblages of conspecific shrew populations in southern California

Flea (Siphonaptera) species richness in the Great Basin Desert and island biogeography theory

Numbers of flea (Siphonaptera) species (flea species richness) on individual mammals should be higher on large mammals, mammals with dense populations, and mammals with large geographic ranges, if mammals are islands for fleas. I tested the first two predictions with regressions of H. J. Egoscue's trapping data on flea species richness collected from individual mammals against mammal size and population density from the literature. Mammal size and population density did not correlate with flea species richness. Mammal geographic range did, in earlier studies. The intermediate-sized (31 g), moderately dense (0.004 individuals/m(2)) Peromyscus truei (Shufeldt) had the highest richness with eight flea species on one individual. Overall, island biogeography theory does not describe the distribution of flea species on mammals in the Great Basin Desert, based on H. J. Egoscue's collections. Alternatively, epidemiological or metapopulation theories may explain flea species richness.

The case of the blood-covered egg: ectoparasite abundance in an arctic goose colony

Since 1991, blood-covered eggs have been noted in nests of Ross’s ( Chen rossii (Cassin, 1861)) and lesser snow ( Chen caerulescens caerulescens (L., 1758)) geese at the Karrak Lake colony, Nunavut, Canada. Fleas ( Ceratophyllus vagabundus vagabundus (Boheman, 1866)) were subsequently observed to be associated with goose nests containing eggs covered with dried blood. We examined prevalence of blood presence on goose eggs and extent of egg coverage with blood in goose nests from 2001 to 2004. Flea abundance in nests was estimated in 2003 and 2004, and was strongly correlated with the proportion of goose egg surface covered by blood, suggesting that degree of blood coverage was a suitable index of flea abundance. Extent of blood fluctuated annually and was correlated with both host characteristics and host habitat factors. Nest bowls used by geese in previous years contained more fleas than did new nest bowls, and fleas were more abundant in older areas of the colony. Flea abundance increased with goose clutch size and was highest in rock and birch habitats. Ceratophyllus vagabundus vagabundus appears to be a new parasite of geese at Karrak Lake; flea abundance may change in response to increased availability of favorable habitat, which is expected if local climate warms.