falco - International Wildlife Consultants Ltd.

What’s new in the literature ?Barton, N.W.H., Fox, N.C., Surai, P.F. and SpeakeB.K. (2002) Vitamins E and A, carotenoids andfatty acids of the raptor egg yolk. Journal of RaptorResearch 36 (1) 33-38.A captive population of falcons was fed a diet containinga known quantity of vitamin A (retinol) and vitamin E(a-tocopherol) for six weeks prior to and during egg-laying.Infertile eggs were analysed for vitamin A, vitaminE, carotenoid and fatty acid composition. Mean, dailyvitamin intake was 29mg Vit E (35IU) and 1157mg Vit A(3363IU). Adjusted mean egg yolk content for infertile,unincubated eggs was 314 mg/g a-tocopherol and 3.06mg/g Vit A. A distinctive feature of the raptor egg yolkis a very high proportion of arachidonic acid which isprobably a reflection of their carnivorous diet. A smallnumber of plasma samples were also available from egglayingfalcons. Mean, plasma vitamin E was 32.2 mg/mland plasma vitamin A 1.02 mg/ml.Casado, E., Balbontin, J., Ferrer, M. (2002) Plasmachemistry in booted eagle (Hieraaetus pennatus) duringbreeding season. Comparative Biochemistry andPhysiology. A, Molecular & Integrative Physiology,131, No.2, pp.233-241Most studies that have examined raptor plasma chemistryhave been conducted on birds living in captivity. Inthis study, we describe typical plasma chemistry valuesindicators of body condition in free-living Booted Eagles,Hieraaetus pennatus, from Donana National Park (Spain).A total of 143 young, 55 adults and one bird of unknownage were caught, banded and sampled between 1996 and2000. Values were compared with those of other raptors.Mean concentrations of creatinine, uric acidand urea were lower in adults than in nestlings, whileglucose, DAT and AAT were lower in nestlings than inadults. Interactions of age/sex affected plasma meanlevels of creatine kinase, glucose, AAT, uric acid andurea. Adult females showed significantly lower levels ofcreatine kinase, uric acid and urea than adult males andnestlings. Adult males had significantly higher levels ofAAT than the other groups. The lowest levels of glucoseand the highest levels of uric acid were found in nestlingfemales. We think the differences in blood parameterscan be explained by differences in size of species, ofindividuals (because of both body condition and sexualdimorphism) and diet.Dawson, R. D., Bortolotti, G. R. (2001) Sex-specificassociations between reproductive output and hematozoanparasites of American kestrels. Oecologia, 126,No.2, pp.193-200Parasites have the potential to decrease reproductive outputof hosts by competing for nutrients or forcing hosts toinvest in immune function. Conversely, reproductive outputmay affect parasite loads if hosts allocate resourcesto reproduction such that allocation to immune functionis compromised. Both hypotheses implicitly have a temporalcomponent. Parasites (Haemoproteus spp.) weresampled both before and after egg laying to examine therelationship between reproductive output (indexed using acombined measure of clutch size, egg volume and initiationdate) and blood parasite loads of American kestrels (Falcosparverius). Parasite loads measured prior to egg layinghad no adverse effects on subsequent reproductive output.Females that previously had large reproductive outputs subsequentlyhad lower parasite intensities than those whoseoutputs were smaller, suggesting that females were capableof allocating energy to both forming clutches and reducingparasite loads. Because male kestrels provide most of theirmate’s energetic needs before, during and after egg laying,mate choice by females may have consequences for theirparasite loads. Females choosing high-quality mates maynot only have increased reproductive output, but may alsoobtain sufficient resources from their mates to enable themto reduce their parasite burdens. Males whose mates hadlarge reproductive outputs were more likely to subsequentlybe parasitized and have more intense infections. For individualmales sampled both before and after egg laying,those whose mates had larger reproductive outputs werealso more likely to become parasitized, or remain parasitized,between sampling periods. Increased parasite loads ofmales may be one mechanism by which the costs of reproductionare paid.Dawson, R. D. and Bortolotti, G. R. (2000) Effects ofhematozoan parasites on condition and return rates ofAmerican kestrels. Auk 117, No.2, pp.373-380The relationship between blood parasites and body conditionof American kestrels (Falco sparverius) was evaluatedduring the breeding season. Females that were infectedwith at least one species of parasite were in poorer conditionthan those without parasites during incubation but notprior to egg laying. It is suggested that the relationshipbetween parasitism and condition was masked before layingbecause of large increases in body mass of females duringegg formation. Reduced condition of males during incubationalso was associated with higher intensity of infectionsby Haemoproteus in one of 2 years. The negative associationbetween condition and intensity of infection suggeststhat blood parasites impose costs on kestrels owing tocompetition for nutrients or allocation of energy by hoststo immune function or tissue repair. Alternatively, kestrelsin poor condition may be more likely to have relapses ofchronic infections, or they may be less able to control newinfections because of resource limitations. In contrast toresults during incubation, during the prelaying period theprevalence of parasites tended to be higher, and in one yearinfections were more intense, among males in good condition.One possible explanation is that body condition ofmales during courtship is an important determinant of thequality of mate they are able to obtain, and males may beaccumulating body reserves at the expense of decreasedimmune function. Return rates of female kestrels to thestudy area declined as the intensity of their Haemoproteusinfections increased, suggesting that blood parasitism isassociated with reduced survival or increased dispersalprobability.24