Testosterone and the allocation of reproductive effort in male house finches ( Carpodacus mexicanus )

2000 ◽  
Vol 48 (5) ◽  
pp. 407-411 ◽  
Author(s):  
A. M. Stoehr ◽  
G. E. Hill
Keyword(s):  
Reproductive Effort ◽  
Carpodacus Mexicanus ◽  
House Finches ◽  
Male House

scholarly journals Plumage Brightness and Breeding-Season Dominance in the House Finch: A Negatively Correlated Handicap?

The Condor ◽  
2000 ◽  
Vol 102 (2) ◽  
pp. 456-461 ◽  
Author(s):  
Kevin J. McGraw ◽  
Geoffrey E. Hill
Keyword(s):  
Breeding Season ◽  
Social Dominance ◽  
Conclusive Evidence ◽  
Carpodacus Mexicanus ◽  
Honest Signal ◽  
Apparent Paradox ◽  
House Finches ◽  
Nonbreeding Season ◽  
Access To Food ◽  
Male House

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.

scholarly journals Carotenoid Pigments in Male House Finch Plumage in Relation to Age, Subspecies, and Ornamental Coloration

The Auk ◽  
2001 ◽  
Vol 118 (4) ◽  
pp. 900-915 ◽  
Author(s):  
Caron Y. Inouye ◽  
Geoffrey E. Hill ◽  
Riccardo D. Stradi ◽  
Robert Montgomerie ◽  
C. Bosque
Keyword(s):  
Total Concentration ◽  
Age Groups ◽  
Bird Species ◽  
Analytical Techniques ◽  
Carpodacus Mexicanus ◽  
Carotenoid Pigments ◽  
Adult Males ◽  
Red Pigments ◽  
House Finches ◽  
Male House

Abstract Like males of many bird species, male House Finches (Carpodacus mexicanus) have patches of feathers with ornamental coloration that are due to carotenoid pigments. Within populations, male House Finches vary in expression of ornamental coloration from pale yellow to bright red, which previous research suggested was the result of variation in types and amounts of carotenoid pigments deposited in feathers. Here we used improved analytical techniques to describe types and amounts of carotenoid pigments present in that plumage. We then used those data to make comparisons of carotenoid composition of feathers of male House Finches at three levels: among individual males with different plumage hue and saturation, between age groups of males from the same population, and between males from two subspecies that differ in extent of ventral carotenoid pigmentation (patch size): large-patched C. m. frontalis from coastal California and small-patched C. m. griscomi from Guerrero, Mexico. In all age groups and populations, the ornamental plumage coloration of male House Finches resulted from the same 13 carotenoid pigments, with 3-hydroxy echinenone and lutein being the most abundant carotenoid pigments. The composition of carotenoids in feathers suggested that House Finches are capable of metabolic transformation of dietary forms of carotenoids. The hue of male plumage depended on component carotenoids, their relative concentrations, and total concentration of all carotenoids. Most 4-keto (red) carotenoids were positively correlated with plumage redness, and most yellow carotenoid pigments were negatively associated with plumage redness, although the strength of the relationship for specific carotenoid pigments varied among age groups and subspecies. Using age and subspecies as factors and concentration of each component carotenoid as dependent variables in a MANOVA, we found a distinctive pigment profile for each age group within each subspecies. Among frontalis males, hatch-year birds did not differ from adults in mean plumage hue, but they had a significantly lower proportion of red pigments in their plumage, and significantly lower levels of the red piments adonirubin and astaxanthin, but significantly higher levels of the yellow pigment zeaxanthin, than adult males. Among griscomi males, hatch-year birds differed from adults in plumage hue but not significantly in pigment composition, though in general their feathers had lower concentrations of red pigments and higher concentrations of yellow pigments than adult males. Both adult and hatch-year frontalis males differed from griscomi males in having significantly higher levels of most yellow carotenoid pigments and significantly lower levels of most red carotenoid pigments. Variation in pigment profiles of subspecies and age classes may reflect differences among the groups in carotenoid metabolism, in dietary access to carotenoids, or in exposure to environmental factors, such as parasites, that may affect pigmentation.

scholarly journals Effects of Coccidial and Mycoplasmal Infections on Carotenoid-Based Plumage Pigmentation in Male House Finches

The Auk ◽  
2000 ◽  
Vol 117 (4) ◽  
pp. 952-963 ◽  
Author(s):  
William R. Brawner ◽  
Geoffrey E. Hill ◽  
Christine A. Sundermann
Keyword(s):  
Mycoplasma Gallisepticum ◽  
Plumage Coloration ◽  
Necessary Condition ◽  
Carpodacus Mexicanus ◽  
Carotenoid Pigments ◽  
Secondary Sexual Traits ◽  
House Finches ◽  
Proximate Factors ◽  
Sexual Traits ◽  
Male House

AbstractCarotenoid pigments produce the ornamental red, orange, and yellow integumentary coloration of many species of animals. Among individuals of a population, the hue and saturation of carotenoid-based ornaments can be extremely variable, and studies of fish and birds have shown that females generally prefer males that display the most saturated and reddest coloration. Consequently, there has been a great deal of interest in determining the proximate factors that affect individual expression of carotenoid-based pigmentation. Parasites might affect production of ornamental coloration, and the Hamilton-Zuk hypothesis proposes that parasitized males will show decreased expression of the secondary sexual traits preferred by females. We found that captive male House Finches (Carpodacus mexicanus) experimentally infected with Isospora spp. (coccidians) and/or Mycoplasma gallisepticum produced carotenoid-based plumage coloration that was significantly less red and less saturated than that of noninfected males. These observations validate a necessary condition of the Hamilton-Zuk hypothesis, but heritable resistance to the pathogens we examined remains to be demonstrated.

scholarly journals The Number of Provisioning Visits by House Finches Predicts the Mass of Food Delivered

The Condor ◽  
2001 ◽  
Vol 103 (4) ◽  
pp. 851-855 ◽  
Author(s):  
Paul M. Nolan ◽  
Andrew M. Stoehr ◽  
Geoffrey E. Hill ◽  
Kevin J. McGraw
Keyword(s):  
Breeding Cycle ◽  
Carpodacus Mexicanus ◽  
Foraging Success ◽  
House Finches ◽  
Video Cameras ◽  
Three Stages ◽  
Male House

Abstract One classic means of assessing variation in avian foraging success and provisioning effort, counting the number of trips to the nest, assumes that parents bring equal amounts of food during each trip. We tested this assumption in male House Finches (Carpodacus mexicanus) by using video cameras to record both the number of nest visits and the mass of food delivered as measured by an electronic balance. We compared the number of feeding visits and mass of food delivered at each of three stages in the nest cycle: incubation, young nestlings, and older nestlings. The number of provisioning trips was significantly correlated with the mass of food provided by a male to his mate or to their offspring during each stage of the nesting cycle. Furthermore, this correlation became stronger as the breeding cycle progressed. These observations support the assumption that, for this species and perhaps others that carry food in their crop, the number of provisioning visits to the nest is a reasonable predictor of the mass of food provided. El Número de las Visitas del Aprovisionamiento de Carpodacus mexicanus Predice la Masa del Alimento Entregada Resumen. Un método clásico para establecer la variación en el éxito de forrajeo y esfuerzo de aprovisionamiento en aves, que consiste en contar el número de viajes hacia el nido, asume que los padres llevan igual cantidad de alimento durante cada viaje. Probamos este supuesto en machos de Carpodacus mexicanus mediante cámaras de video que registraron tanto el número de visitas al nido como el peso del alimento entregado, este último medido mediante una balanza electrónica. Comparamos el número de visitas al nido y el peso del alimento entregado en cada uno de los tres estados del ciclo de nidificación: incubación, pichones jóvenes y pichones tardíos. El número de viajes de aprovisionamiento se correlacionó positivamente con el peso del alimento provisto por un macho a su pareja o a su progenie en cada estado del ciclo de nidificación. Además, esta correlación se hizo más fuerte a medida que el ciclo de nidificación progresó. Estas observaciones apoyan el supuesto que, al menos para esta especie y otras que transportan alimento en el buche, el número de visitas de aprovisionamiento al nido predice razonablemente bien la masa de alimento provista.

Carotenoid-based plumage coloration and aggression during molt in male house finches

Behaviour ◽  
2007 ◽  
Vol 144 (2) ◽  
pp. 165-178 ◽  
Author(s):  
William Medina-Jerez ◽  
Heather Adams ◽  
Kevin McGraw
Keyword(s):  
Male Dominance ◽  
Plumage Coloration ◽  
Visual Signal ◽  
Carpodacus Mexicanus ◽  
Plumage Color ◽  
House Finches ◽  
Clear Link ◽  
Access To Food ◽  
The Relationship ◽  
Male House

AbstractBirds often use colorful traits to mediate resource competitions, and typically individuals with bright or large patches of color are more competitive than or dominant to those with drab or small color patches. Male House Finches (Carpodacus mexicanus) are an exception, however, as drab males tend to be more aggressive than bright males during the breeding season and in winter. One hypothesis for this 'negatively correlated handicap' is that drab male house finches, being comparatively sexually unattractive and in poor health and condition, have more to gain by elevating aggression and increasing access to food and pursuit of (especially extra-pair) mates. It would seem important then to test this hypothesis during the period of molt, when birds are actively acquiring the foods and carotenoid pigments that make them colorful and a time in which there is a clear link between plumage color and nutrition/health in this species. We conducted two captive dominance experiments with male House Finches from the southwestern United States (their native range) to examine the relationship between carotenoid-based plumage coloration and aggression during molt. In the first experiment, where birds exhibited their natural, currently growing plumage color, we found that drab males were significantly more aggressive than bright males. However, when plumage colors were manipulated with art markers in a second experiment, color display was no longer significantly predictive of agonistic outcomes. These results suggest that: (1) drab male dominance is not an artifact in eastern US populations and instead is a conserved property of native and non-native House Finches, (2) like in our previous studies in winter, plumage color is correlated with dominance but does not serve as a visual signal of social status in this species, and (3) drab males should have a competitive advantage over access to important carotenoid-rich foods during molt, but apparently do not become as colorful because they do not adequately locate carotenoid-rich foods or do not use them efficiently for energetic or health reasons, which are perhaps exacerbated by elevated testosterone levels.

Plumage color as a dynamic trait: carotenoid pigmentation of male house finches (Carpodacus mexicanus) fades during the breeding season

2004 ◽  
Vol 82 (5) ◽  
pp. 734-738 ◽  
Author(s):  
Kevin J McGraw ◽  
Geoffrey E Hill
Keyword(s):  
Breeding Season ◽  
Breeding Period ◽  
Carpodacus Mexicanus ◽  
Plumage Color ◽  
Direct Function ◽  
House Finches ◽  
Dynamic Trait ◽  
Mate Switching ◽  
Carotenoid Pigmentation ◽  
Male House

Evolutionary biologists studying sexually selected bird plumage generally consider this trait to be static throughout a breeding season and assign trait values to individuals on the basis of single measurements. We investigated the propensity for carotenoid-based color of feather patches in male house finches (Carpodacus mexicanus ( Muller, 1776)) to change during the breeding period. We recaptured and rescored 63 males and found that the hue of feathers faded significantly over the season. The degree of hue change was a direct function of the amount of time between plumage scores; feathers faded more as the interval between measurements increased. The magnitude of hue change was not, however, related to an individual's age or initial plumage redness, which suggests that certain birds are not more or less prone to fading. Collectively, these findings imply that researchers should more carefully track plumage color expression during the course of a year, as seasonal color shifts may have important consequences for late-season male–male competitive interactions and flexible female mating tactics (e.g., social mate switching, choice of extra-pair partners). Potential mechanisms for this seasonal plumage color shift are discussed.

Nest mites (Pellonyssus reedi) and the reproductive biology of the house finch (Carpodacus mexicanus)

2000 ◽  
Vol 78 (12) ◽  
pp. 2126-2133 ◽  
Author(s):  
Andrew M Stoehr ◽  
Paul M Nolan ◽  
Geoffrey E Hill ◽  
Kevin J McGraw
Keyword(s):  
Reproductive Biology ◽  
Carpodacus Mexicanus ◽  
House Finch ◽  
East Central ◽  
House Finches ◽  
Male Plumage ◽  
Initial Appearance ◽  
Almost All ◽  
Mite Infestations ◽  
Male House

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.

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