Suitability of anodic stripping voltammetry for routine analysis of venous blood from raptors

Lead (Pb) poisoning is a significant threat faced by raptors. Hence, rapid Pb diagnosis has become a priority during the admission of raptors in wildlife recovery centers, and bench-top analyzers, such as LeadCare II ®, are routinely employed for this purpose. However, this device has been designed for conducting analyses of human blood Pb levels (BLLs), and the validity of this methodology for whole blood from raptors has, to date, rarely been assessed. In addition, a recent recall by the US Food and Drug Administration has recommended discontinuing the use of this analyzer for human venous blood because it may underestimate the BLL. We evaluated the precision of BLL measurements taken with LeadCare II by comparing them with those obtained with inductively coupled plasma mass spectrometry (ICP-MS). Our sample contained venous blood from 105 raptors belonging to 4 species. The results showed a good correlation between the 2 techniques (Spearman's r = 0.927, p < 0.0001). The mean BLL with ICP-MS was 19.6 μg/dL; it was found to be 18.7 μg/dL with LeadCare II. A Bland-Altman analysis indicated that the bias between the mean differences was only 0.5 μg/dL, but it had a high standard deviation of bias (5.7 μg/dL) and 95% limits of agreement from -10.75 to 11.74 μg/dL. The present results indicated that LeadCare II has an overall sensitivity of 71.8% and a positive predictive value of 76.3%. The specificity of LeadCare II for detecting animals with low BLL (<3.4 μg/dL) was 96.4%, and the negative predictive value (the probability that a value below the limit of detection of LeadCare II has a true correspondence with the actual value) was 100%. The present results indicated that, although LeadCare II might be imperfect in the estimation of BLLs in raptors, it performs reasonably well and might be employed in the clinical setting to assess patients potentially suffering from Pb poisoning. Environ Toxicol Chem 2019;38:737-747. © 2018 SETAC.

Lead in piscivorous raptors during breeding season in the Chesapeake Bay region of Maryland and Virginia, USA

Sources of lead exposure of many bird species are poorly understood. We analyzed blood lead concentrations from osprey (n = 244; Pandion haliaetus) and bald eagles (n = 68; Haliaeetus leucocephalus) and documented potential sources of lead they may encounter. Adult bald eagles had higher blood lead concentrations than did adult osprey. However, blood lead concentrations of nestlings were similar for both species. Although 62% of osprey had detectable lead concentrations ( x¯  = 1.99 ± 4.02 μg/dL, mean ± standard deviation [SD]), there was no difference in the detection frequency or lead concentrations between osprey adults and nestlings. Likewise, we found no differences in the detection frequency or lead concentrations in osprey adults and nestlings from high- and low-salinity areas. Of the bald eagle samples tested, 55% had detectable lead levels ( x¯  = 6.23 ± 10.74 μg/dL). Adult bald eagles had more detectable and higher lead concentrations than did nestlings or pre-adults. Among environmental samples, paint had the highest lead concentrations, followed by sediment, blue catfish (Ictalurus furcatus), and gizzard shad (Dorosoma cepedianum). There was no correlation between blood lead concentrations of osprey adults and their offspring. Our results indicate that, in the Chesapeake Bay region of Maryland and Virginia (USA), there are multiple sources by which piscivorous raptors may be exposed to lead. Environ Toxicol Chem 2019;38:862-871. © Published 2019 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Food safety in scavenger conservation: Diet-associated exposure to livestock pharmaceuticals and opportunist mycoses in threatened Cinereous and Egyptian vultures

Pharmaceuticals from veterinary treatments may enter terrestrial food webs when medicated livestock are available to wildlife in supplementary feeding stations aimed at the conservation of endangered scavengers. Here, we hypothesized that the exposure risk to livestock fluoroquinolones, as indicators of pharmaceutical burden in food, is related to the variable reliance of scavengers on domestic versus wild animal carcasses. Since the misuse of broad-spectrum antibiotics is a major predisposing factor for opportunistic mycoses, we evaluated disease signs potentially associated with diet-dependent drug exposure in nestlings of two threatened vultures. A greater occurrence (100%, n=14) and concentration of fluoroquinolones (mean±SD=73.0±27.5µgL^-1, range=33.2-132.7), mostly enrofloxacin, were found in Cinereous vultures, Aegypius monachus, due to their greater dependence on livestock carcasses than Egyptian vultures, Neophron percnopterus (fluoroquinolones occurrence: 44%, n=16, concentration: 37.9±16.6µgL^-1, range=11.5-55.9), which rely much more on carcasses of wild animals (42% of remains vs. 23% in the cinereous vulture). The chaotic, chronic and pulsed ingestion of these drugs throughout nestling development is proposed as one of the most plausible explanations for the high occurrence and intensity of oral Candida-like lesions in nestling vultures. The high occurrence of fluoroquinolone residues and disease hindered the probing of a cause-effect relationship between both factors in individual vultures. This relationship could be evaluated through a population-based approach by sampling vultures not exposed to these drugs. The high dependence of vultures on domestic animals today compared to past decades and the growing intensification of livestock farming, imply an expected increase in the impact of pharmaceuticals on scavenger populations. This requires further evaluation due to potential consequences in biodiversity conservation and environmental health. We encourage the prioritization of efforts to promote the use of less medicated free-ranging livestock carcasses left in the countryside, rather than stabled stocks made available in vulture restaurants. Additionally, attention should be paid to the population recovery of wild species that dominated scavenger diets in the past.

Diet exposure to technical hexabromocyclododecane (HBCD) affects testes and circulating testosterone and thyroxine levels in American kestrels (Falco sparverius)

Hexabromocyclododecane (HBCD) is a high-production-volume, brominated flame-retardant that is used in items such as polystyrene foams. HBCD has been detected in the environment, wildlife tissues and in humans globally with some of the highest recorded levels in predatory birds. This study examined the effects of exposure to environmentally relevant levels of HBCD on the reproductive physiology of captive male American kestrels (Falco sparverius), a predatory bird. Two sets of males were used: one group not housed with females (unpaired: nc=12, nHBCD=10) and the second group housed with females (breeding: nc=10, nHBCD=20). All treatment birds were exposed to 0.51 μg HBCD/g kestrel/day technical HBCD, and controls to safflower oil only, injected into their food during seasonal testicular development. Unpaired males were exposed for 3 weeks and euthanized for testicular analysis. Breeding males were exposed for 3 weeks prior to pairing and throughout the courtship period. The HBCD-exposed unpaired males had heavier testes (p≤0.017) and a trend towards more seminiferous tubules containing elongated spermatids (p=0.052). There was also a moderate increase in plasma testosterone concentrations (p=0.056) compared to controls. In breeding males, testosterone levels increased during courtship to culminate in higher levels than controls by the time the first egg was laid (p=0.010) and circulating free and total T4 was reduced throughout. The number of sperm cells reaching the perivitelline layer of the first egg for breeding males did not differ between the two groups. This study is the first report that HBCD exposure at environmentally relevant levels alters reproductive physiology in male birds and suggests that birds may be more sensitive to HBCD than mammals.

Mercury in the blood and eggs of American kestrels fed methylmercury chloride

American kestrels (Falco sparverius) were fed diets containing methylmercury chloride (MeHg) at 0, 0.6, 1.7, 2.8, 3.9, or 5.0 µg/g (dry wt) starting approximately eight weeks before the onset of egg laying. Dietary treatment was terminated after 12 to 14 weeks, and unhatched eggs were collected for Hg analysis. Blood samples were collected after four weeks of treatment and the termination of the study (i.e., 12-14 weeks of treatment). Clutch size decreased at dietary concentrations above 2.8 µg/g. The average total mercury concentration in clutches of eggs and in the second egg laid (i.e., egg B) increased linearly with dietary concentration. Mercury concentrations in egg B were approximately 25% lower than in the first egg laid and similar in concentration to the third egg laid. Mercury concentrations in whole blood and plasma also increased linearly with dietary concentration. Total Hg concentrations in June blood samples were lower than those in April, despite 8 to 10 weeks of additional dietary exposure to MeHg in the diet. This is likely because of excretion of Hg into growing flight feathers beginning shortly after the start of egg production. The strongest relationships between Hg concentrations in blood and eggs occurred when we used blood samples collected in April before egg laying and feather molt.

Reproductive endocrinology of wild, long-lived raptors

The last decades have witnessed a surge of studies analyzing the role of sex hormones on the behavior and ecology of wild bird populations, allowing a more integrated view of the evolution of avian physiology and life histories. Despite a marked progress, field studies show a considerable bias towards research on specific phylogenetic groups, neglecting a significant fraction of the class Aves. Here we analysed changes in the circulating levels of sex steroids in relation to reproductive behaviour in wild black kites (Milvus migrans), a long-lived and socially monogamous Accipitridae raptor. Males and females displayed a single seasonal peak of circulating testosterone (males) and estradiol (females) during pre-laying and laying. Absolute male testosterone levels were low even at the seasonal maximum and remained below detection limits in females. The latter results supports the idea that avian species establishing long-term pair bonds require lower amounts of circulating androgens for reproduction. Circulating progesterone showed a single seasonal peak in females and males, but their timing (during Incubation and Post-brooding respectively) did not overlap. The fact that females black kites perform the majority of incubation and males provide the majority of care to fledglings suggests that progesterone is involved in the expression of parental behaviors.

Raptor ecotoxicology in Spain: a review on persistent environmental contaminants

Initial studies on the pressure from environmental contaminants on raptor populations in Spain date back to the 1980s, and they have been carried out from a range of viewpoints using a range of sentinel raptor species. However, there is no national monitoring scheme, and therefore the research carried out has been sporadic both spatially and temporally. The exposure to metals has not varied over time, except in the case of lead, whose concentration in eggs and tissues has diminished. In general, the concentrations of metals detected in raptor samples from Spain are generally low and not sufficient to produce toxic effects. Excepting DDT and DDE, most organochlorine-based pesticides in raptors from Spain have diminished over the last 2 decades. The concentrations of DDE found in the eggs of various species could in part explain problems in the reproductive success of raptors in Spain.

Hematologic and biochemical reference ranges for captive California condors (Gymnogyps californianus)

To provide proper medical evaluation and care for the endangered California condor (Gymnogyps californianus), veterinarians need accurate hematologic and biochemical reference ranges. A retrospective study of blood samples from captive California condors housed at the San Diego Wild Animal Park assessed the samples by sex and age of condor to determine serum biochemical and hematologic reference ranges, including lead and zinc levels. Condors were grouped by age as follows: group 1 included birds less than 30 days of age; group 2 included birds between 30 days and 6 mo of age; group 3 included birds between 6 mo and 5 yr of age; group 4 included all birds greater than 5 yr of age. Significant differences between sexes included higher chloride, cholesterol, and total plasma protein concentration in males as compared to females (P < 0.05). Significant differences between age groups were identified in glucose, potassium, phosphorus, calcium, albumin, total plasma protein, globulin, cholesterol, bile acid, and zinc concentrations, as well as aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, and creatine phosphokinase activities (P < 0.05). Additionally, significant differences between age groups were noted in white blood cell count, hematocrit, heterophils, lymphocytes, and eosinophils (P < 0.05). A steady increase in glucose and a decrease in alkaline phosphatase and lactate dehydrogenase activities, as well as cholesterol, bile acid, calcium, and phosphorus concentrations, were correlated with age (P < 0.05). Following application of statistical analysis, condors less than 6 mo of age were identified as unique compared to older cohorts; therefore, two reference ranges are proposed by calculating a 90% confidence interval. Reference ranges obtained from other published avian data, including those for psittaciformes, ratites, galliformes, anseriformes, and raptors, were similar to condors in this study.

Glycated hemoglobin and albumin reflect nestling growth and condition in American kestrels

Blood chemistry can be used to assess physiological state and condition. Levels of glycated hemoglobin (GHb), which integrates blood glucose levels over a period of weeks, may provide a way to assess resource intake. I tested whether GHb reflects offspring quality by comparing growth rates of nestling American kestrels (Falco sparverius) with GHb levels at 24 days of age. Nestlings that gained structural size faster had higher levels of GHb than did slower growing nestlings. There was no difference in GHb levels between males and females, although females are larger. In addition, I tested whether albumin levels, a measure of protein storage, were correlated with nestling growth and body condition (reflected in residual body mass). Larger individuals, measured by both absolute body mass and by residual body mass, had larger levels of albumin. This was due in part to females having higher albumin levels. Interestingly, there was no correlation between GHb and albumin, suggesting that both measures are necessary to assess physical condition in nestling kestrels. These results suggest that blood chemistry can reflect offspring condition measures and may provide a way to assess offspring quality that reflects conditions experienced by offspring over longer periods through measurements at a single time point.

PLASMA B-ESTERASE ACTIVITIES IN EUROPEAN RAPTORS

B-esterases are serine hydrolases composed of cholinesterases, including acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), and carboxylesterase (CbE). These esterases, found in blood plasma, are inhibited by organophosphorus (OP) and carbamate (CB) insecticides and can be used as nondestructive biomarkers of exposure to anticholinesterase insecticides. Furthermore, B-esterases are involved in detoxification of these insecticides. In order to establish the level of these enzymes and to have reference values for their normal activities, total plasma cholinesterase (ChE), AChE and BChE activities, and plasma CbE activity were determined in 729 European raptors representing 20 species, four families, and two orders. The diurnal families of the Falconiforme order were represented by Accipitridae and Falconidae and the nocturnal families of the Strigiforme order by Tytonidae and Strigidae. Intraspecies differences in cholinesterase activities according to sex and/or age were investigated in buzzards (Buteo buteo), sparrowhawks (Accipiter nisus), kestrels (Falco tinnunculus), barn owls (Tyto alba), and tawny owls (Strix aluco). Sex-related differences affecting ChE and AChE activities were observed in young kestrels (2-3-mo-old) and age-related differences in kestrels (ChE and AChE), sparrowhawks (AChE), and tawny owls (ChE, AChE, and BChE). The interspecies analysis yielded a negative correlation between ChE activity and body mass taking into account the relative contribution of AChE and BChE to ChE activity, with the exception of the honey buzzard (Pernis apivorus). The lowest ChE activities were found in the two largest species, Bonelli's eagle (Hieraaetus fasciatus) and Egyptian vulture (Neophron percnopterus) belonging to the Accipitridae family. The highest ChE activities were found in the relatively small species belonging to the Tytonidae and Strigidae families and in honey buzzard of the Accipitridae family. Species of the Accipitridae, Tytonidae, and Strigidae families were characterized by a BChE contribution that dominated the total ChE activity, while in the species of the Falconidae family, AChE activity dominated. With the exception of the barn owl, CbE activity (eserine-insensitive alpha-naphthyl acetate esterase [alpha-NAE] activity) in all species was almost absent or very low. The values obtained in this study for ChE, AChE, and BChE activities and the AChE:BChE ratios for buzzard, kestrel, barn owl, and tawny owl provide a good estimate of the normal values in free-living individuals of these European species. They can be used as a baseline to evaluate the effect of anticholinesterase insecticides in the field.

Hemophilia D factor (factor XII), red-cell deformability and platelet aggregates in raptors

In a spectrum of raptorial birds hemorrheologic factors were determined compared to normal human values. Significant findings were that Hageman factor (factor XII) levels were very low, the red-cell filteration rate was low, but the platelet-aggregate ratio was in the normal range. Relatively large, nucleated red cells appeared to be less flexible-deformable--than normal human red cells. Microvessel density (MVD) appeared to be in the normal range, but increased average capillary diameter may explain the lack of microvascular abnormalities. Hageman factor deficiency in raptors is comparable to human hemophilia D. However, the mechanisms of the lack of obvious thromboembolic and/or hemorrhagic phenomena may require further investigation.

Experimental lead poisoning in turkey vultures (Cathartes aura)

Lead-induced mortality appears to have been a major factor in the decline of the California condor (Gymnogyps californianus). We orally dosed turkey vultures (Cathartes aura) with BB-sized lead shot from January 1988 through July 1988 to determine physiologic response (delta-aminolevulinic acid dehydratase inhibition, erythrocyte protoporphyrin levels, anemia), diagnostic tissue lead concentrations (blood, liver, and kidney), and comparative sensitivity of this species. Two turkey vultures died and two became so intoxicated they were euthanized. Overall, responses of measured parameters were comparable to other species exposed to lead although there was considerable individual variation. Survival time (143-211 days), even with the large numbers of shot and constant redosing, was much longer than reported for other species of birds, suggesting considerable tolerance by turkey vultures to the deleterious effects of lead ingestion. Based on these observations, turkey vultures appear to be poor models for assessing the risk of lead poisoning to California condors or predicting their physiologic response.

Investigations into the uricolytic properties of urate oxidase in a granivorous (Columba livia domestica) and in a carnivorous (Buteo jamaicensis) avian species

To study the uricolytic properties of urate oxidase in granivorous and carnivorous birds, experiments were conducted in pigeons (Columba livia domestica) and Red-tailed Hawks (Buteo jamaicensis). Plasma concentrations of allantoin and uric acid were determined at various times in experimental groups before and after receiving 100, 200, and 600 U/kg urate oxidase once daily and were compared with controls. All regimens caused a significant decrease in plasma uric acid concentrations within 2 days after the first administration, when compared with controls. Furthermore, both doses used in Red-tailed Hawks (200 and 100 U/kg) caused a significant postprandial suppression of plasma uric acid concentrations. Plasma allantoin concentrations were significantly higher when compared with controls. The ability of urate oxidase to prevent the physiological postprandial hyperuricaemia in Red-tailed Hawks and to reduce plasma uric acid concentrations to undetectable levels, shows the great potential of this drug for treating avian hyperuricaemia.

Further studies on the use of allopurinol to reduce plasma uric acid concentrations in the Red-tailed Hawk (Buteo jamaicensis) hyperuricaemic model

The present paper reports the effects of allopurinol in a raptor hyperuricaemic model. The study was performed as a follow-up to previous experiments wherein allopurinol was used in doses of 100 and 50 mg/kg, and was proved to be toxic at these higher dose rates. To investigate whether 25 mg/kg (semel in die) s.i.d. allopurinol is a safe and effective dose in Red-tailed Hawks (Buteo jamaicensis) to reduce plasma uric acid concentrations, experimental studies were performed using the physiologically occurring postprandial hyperuricaemia. Preprandial and postprandial plasma concentrations of xanthine, hypoxanthine, allopurinol, oxypurinol and uric acid were established by high-performance liquid chromatography at various time intervals after receiving allopurinol (25 mg/kg SID) or placebo. No significant differences were observed between the experimental and the control group. These results indicate that this dose is safe to administer; however, this dose failed to cause a significant effect on plasma uric acid concentrations. Because of the low therapeutic ratio of allopurinol in Red-tailed Hawks, follow-up studies have concentrated on an alternative for the treatment of hyperuricaemia, namely urate oxidase.

Persistent organochlorine pesticides detected in blood and tissue samples of vultures from different localities in South Africa

Gas chromatography was used to establish the presence of quantifiable residues of 14 persistent chlorinated hydrocarbon pollutants in whole blood, clotted blood, heart, kidney, liver and muscle samples obtained from individual African whitebacked (Pseudogyps africanus), Cape griffon (Gyps coprotheres) and Lappetfaced (Torgos tracheliotos) vultures from different localities in South Africa. The levels of pesticides measured in whole blood samples of live specimens were compared between nestlings from two natural breeding colonies, adults from a wildlife area and birds held in captivity. Statistically significant (P<0.05) differences between populations were detected in geometric means calculated for gamma-BHC (lindane), alpha(cis)-chlordane and alpha-endosulfan. Five of the organochlorine contaminants displayed significant variations between concentrations detected in the clotted blood, organs and muscles excised from vulture carcasses. This includes residues of gamma-BHC, alpha-chlordane, dieldrin, beta-endosulfan and heptachlor epoxide. Values of the respective biocides measured in vulture samples were generally low in comparison to results documented for a number of avian species. Although no threat is posed by any of the organochloride pesticides, continual monitoring of especially breeding colonies is recommended. Furthermore, the suitability of African whitebacked vulture nestlings as basic bioindicators is highly advocated.

Hematological, protein electrophoresis and cholinesterase values of free-living nestling peregrine falcons in Spain

Protein electrophoresis, hematological and cholinesterase values were determined in 32 nestling free-living peregrine falcons (Falco peregrinus) (15- to 27-days-old) in order to establish normal reference values for this population. The following values (mean +/- SD) were observed: prealbumin 0.31 +/- 0.04 g/dl, albumin 1.25 +/- 0.06 g/dl, alpha1 and alpha2-globulin 0.23 +/- 0.02 and 0.16 +/- 0.02 g/dl respectively, beta-globulin 1.02 +/- 0.05 g/dl, gamma-globulin 0.060 +/- 0.08 g/dl, total protein 3.79 +/- 0.18 g/dl, 21.26 +/- 1.30 white blood cells/microl (1 x 10(3)), 2.17 +/- 0.07 red blood cells/microl (1 x 10(6)), packed cell volume 37.58 +/- 0.82%, hemoglobin 20.96 +/- 0.29 g/dl, heterophils 61.14 +/- 2.50% and cholinesterase 1,184 +/- 75 IU/L. There were no difference in any of these parameters among males and females. The hematological values obtained could be considered as representative values in free-living nestling peregrine falcons.

Genetics, local environment and health as factors influencing plasma carotenoids in wild American kestrels (Falco sparverius)

Carotenoids are important as pigments for bright coloration of animals, and as physiologically active compounds with a wide array of health-related functions. Carotenoid-dependent coloration may have evolved as a signal to conspecifics; however, factors that may limit availability of carotenoids are poorly known. We investigated how the acquisition of carotenoids may be constrained by availability in the environment, diet, genetic make-up and health status of wild American kestrels (Falco sparverius). Plasma concentrations of siblings at the time of fledging showed a high degree of resemblance; however, a cross-fostering experiment revealed that variance was largely explained by nest of rearing, rather than nest of origin, thus indicating a low genetic component. A multivariate analysis of attributes of nestlings (sex, size, plasma proteins, immune function), parental reproduction (laying date, clutch size) and rearing conditions (brood size, size hierarchy, nestling mortality) showed only a small significant effect of leucocyte differentials on carotenoid concentrations of nestlings. A strong environmental effect on plasma carotenoids was demonstrated by levels of adult kestrels being correlated within mated pairs, and having a significant association with the abundance of voles, the primary prey species, per territory.

Pharmacokinetics of piperacillan after intramuscular injection in red-tailed hawks (Buteo jamaicensis) and great horned owls (Bubo virginianus)

This study characterized and compared the pharmacokinetics of piperacillin after single 100 mg/kg i.m. injections in nine red-tailed hawks (Buteo jamaicensis) and five great horned owls (Bubo virginianus) over 48 hr by a modified agar well diffusion microbial inhibition assay. The mean maximum plasma piperacillin concentrations were 204 microg/ml and 221 microg/ml for the hawks and owls, respectively, and times of maximum concentrations were 15 min and 30 min, respectively. The calculated mean terminal elimination half-lives were 77 min in the hawks and 118 min in the owls. Area-under-the-curve values were 218 +/- 52 microg x hr/ml in the hawks and 444 +/- 104 microg x hr/ml in the owls. On the basis of the most common minimal inhibitory concentration (90%) for various bacterial isolates from clinical samples of 8 microg/ml, analysis of the data suggests that the maximum dosing interval for piperacillin at 100 mg/kg in medium sized raptors should be 4-6 hr.

Pansteatitis in a free-ranging red-tailed hawk (Buteo jamaicensis)

A free-ranging juvenile female red-tailed hawk (Buteo jamaicensis) that was unable to fly was admitted to a rehabilitation center and died 1 day later. Hematology and serum chemistry abnormalities included moderate regenerative anemia, elevated creatine kinase, and hyperphosphatemia. Necropsy revealed a generalized steatitis, and histology showed a necrotizing and granulomatous pansteatitis with intralesional pigment compatible with ceroid. There was also moderate diffuse myodegeneration, mild multifocal cardiomyopathy, and mild multifocal hepatic necrosis. These changes and lesions resemble those caused by vitamin E deficiency in mammals and fish-eating birds.

Prevalence of haematozoa in birds of prey in Catalonia, north-east Spain

Blood samples from birds of prey, 95 Strigiformes and 190 Falconiformes, were examined for the presence of haematozoan parasites. The birds had been admitted to a raptor recovery centre in Catalonia, north-east Spain. Parasites were counted in positive smears. A second blood sample was obtained from 99 birds at least seven days after their arrival at the centre. Haematozoa were detected in all seven species of Strigiformes and in nine of 19 species of Falconiformes. The overall prevalences in the two groups were significantly different, 30.5 per cent and 46.3 per cent in the nocturnal and diurnal raptors, respectively. Eleven species of haematozoan parasites were identified. The genus most commonly detected in members of the nocturnal Strigiformes was Leucocytozoon, followed by Haemoproteus, Plasmodium and Trypanosoma. In the diurnal Falconiformes only Leucocytozoon and Haemoproteus were detected. The highest infection rates were found in Accipiter nisus (sparrow hawks), Accipiter gentilis (goshawks) and Athene noctua (little owls). Relapses were detected in 9 per cent of the birds sampled twice. The highest intensity of infection (6.2 per cent) was observed in a Buteo buteo (buzzard) infected with Haemoproteus.