scholarly journals Androgen control of immunocompetence in the male house finch, Carpodacus mexicanus Muller

2005 ◽  
Vol 208 (7) ◽  
pp. 1287-1295 ◽  
Author(s):  
P. Deviche
2000 ◽  
Vol 78 (12) ◽  
pp. 2126-2133 ◽  
Author(s):  
Andrew M Stoehr ◽  
Paul M Nolan ◽  
Geoffrey E Hill ◽  
Kevin J McGraw

We investigated the effects of a hematophagous nestling mite (Pellonyssus reedi, Acari: Macronyssidae) on the reproductive biology of the house finch (Carpodacus mexicanus) in east-central Alabama, U.S.A. Mites were absent from nests for the first half of the breeding season, but after their initial appearance they increased in number and were present in almost all nests. High nest-mite levels were associated with decreased nestling mass and hematocrit, but not with decreased nestling tarsus length. Experimental elimination of mites from some nests confirmed that the effects observed were mite-induced, not seasonal. The plumage colour of breeding adult male house finches was not correlated with nest-mite levels, nor did it appear that redder males' offspring suffered less from the effects of mites. Adult house finches fed nestlings from highly parasitized nests less often than those from nests with few or no mites. It appears unlikely that mites are directly involved in the sexual selection of bright male plumage coloration in this population of house finches. However, it is known that early-nesting females preferentially pair with redder males, therefore the benefit of nesting early and avoiding mite infestations is greater for redder male house finches.


1986 ◽  
Vol 22 (3) ◽  
pp. 420-422 ◽  
Author(s):  
Douglas E. Docherty ◽  
Renee I. Romaine Long

The Auk ◽  
1983 ◽  
Vol 100 (1) ◽  
pp. 180-187 ◽  
Author(s):  
Dennis M. Power

Abstract Coefficients of variation and generalized variances are compared for nine morphological characters from five mainland and four island populations of the House Finch (Carpodacus mexicanus). The purpose is to test the idea that variability is reduced in isolated populations and that there is a "population variation parameter" that determines the level of variation in most characters. Variability is greater in bill characters for Guadalupe and San Benito Islands than for mainland and other island populations. There are no consistent differences among samples in variability of wing, tail, or hind-limb characters, except for a tendency toward increased tarsus-length variability in a southern Baja California population and reduced variability in this character in San Clemente Island and Guadalupe Island populations. In bill characters, increased variability is found in the most divergent populations. The results do not support the generalization that geographic (= genetic) isolation per se causes much of a change in variability in island populations of birds, nor is there support for the idea of a pervasive quality of the gene pool that determines the level of variability in most characters.


The Auk ◽  
2001 ◽  
Vol 118 (2) ◽  
pp. 327-333 ◽  
Author(s):  
Barry K. Hartup ◽  
Jean M. Bickal ◽  
Andre A. Dhondt ◽  
David H. Ley ◽  
George V. Kollias

Abstract Conjunctivitis, an infectious disease caused by Mycoplasma gallisepticum (MG), has produced a significant decline in eastern House Finches (Carpodacus mexicanus) of North America. In this paper, we present findings from two complementary studies designed to clarify annual and seasonal trends of MG infections in House Finches from the northeastern United States. The first was a field study of House Finches common to urban and residential habitat from Mercer County, New Jersey. We documented conjunctivitis in 11% (188/1,651) of the birds examined. Conjunctivitis prevalence in House Finches ranged from 0 to 43% per month, and exhibited marked seasonal fluctuation (elevations during fall and winter months and lower disease prevalence during the breeding season). There was excellent intermethod agreement on disease prevalence when measured by either presence of physical signs (conjunctivitis) or MG infection (kappa = 0.75). During the peak of the breeding season (April through June), conjunctivitis was present in a greater proportion of males lacking a cloacal protuberance than males with a cloacal protuberance (P < 0.01), but was similar between breeding and nonbreeding females. The second study, a volunteer survey, revealed the proportion of northeastern U.S. monitoring sites with at least one diseased House Finch each month ranged from a peak of 59% (August 1995) to a minimum of 12% (July 1999). Subsequent to the epidemic peak of disease in 1995, a series of recurring cycles occurred, with elevations in those proportions noted in late fall and winter and minima during the breeding season. Mycoplasmal conjunctivitis now appears endemic among House Finches of that region and demonstrates dynamics consistent with annual variation in host density.


The Condor ◽  
2000 ◽  
Vol 102 (2) ◽  
pp. 456-461 ◽  
Author(s):  
Kevin J. McGraw ◽  
Geoffrey E. Hill

Abstract A variety of observations indicate that the carotenoid-based coloration of male House Finches (Carpodacus mexicanus) is an honest signal of quality. Plumage redness in this species positively reveals male nutritional condition, over-winter survival, and nest attentiveness. As a result, in the breeding season, male House Finches with brighter ornamental plumage are preferred by females as social mates over males with drabber plumage. In the nonbreeding season, however, bright red plumage does not seem to confer an advantage in aggressive interactions, as males with drabber plumage tend to dominate males with brighter plumage. We investigated this apparent paradox by conducting a breeding-season dominance experiment using captive males. We paired unfamiliar males of contrasting plumage brightness in a series of dominance trials during the breeding season and found that drabber males were dominant to brighter males in competition for access to food. Furthermore, in two captive flocks of males, plumage brightness was significantly negatively associated with social dominance. Although we have no conclusive evidence to explain why drab male House Finches are dominant to bright males throughout the year, we believe that motivational asymmetry may contribute to the observed negative correlation between signal intensity and signaler quality (“negatively correlated handicap”). Drab males may be more willing to compete for access to food or to females than are bright males because of the nutritional and/or mating disadvantages from which they suffer.


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