Blood Parasites in Owls with Conservation Implications for the Spotted Owl (Strix occidentalis)

The three subspecies of Spotted Owl (Northern, Strix occidentalis caurina; California, S. o. occidentalis; and Mexican, S. o. lucida) are all threatened by habitat loss and range expansion of the Barred Owl (S. varia). An unaddressed threat is whether Barred Owls could be a source of novel strains of disease such as avian malaria (Plasmodium spp.) or other blood parasites potentially harmful for Spotted Owls. Although Barred Owls commonly harbor Plasmodium infections, these parasites have not been documented in the Spotted Owl. We screened 111 Spotted Owls, 44 Barred Owls, and 387 owls of nine other species for haemosporidian parasites (Leucocytozoon, Plasmodium, and Haemoproteus spp.). California Spotted Owls had the greatest number of simultaneous multi-species infections (44%). Additionally, sequencing results revealed that the Northern and California Spotted Owl subspecies together had the highest number of Leucocytozoon parasite lineages (n = 17) and unique lineages (n = 12). This high level of sequence diversity is significant because only one Leucocytozoon species (L. danilewskyi) has been accepted as valid among all owls, suggesting that L. danilewskyi is a cryptic species. Furthermore, a Plasmodium parasite was documented in a Northern Spotted Owl for the first time. West Coast Barred Owls had a lower prevalence of infection (15%) when compared to sympatric Spotted Owls (S. o. caurina 52%, S. o. occidentalis 79%) and Barred Owls from the historic range (61%). Consequently, Barred Owls on the West Coast may have a competitive advantage over the potentially immune compromised Spotted Owls

Diversity, Loss, and Gain of Malaria Parasites in a Globally Invasive Bird

Invasive species can displace natives, and thus identifying the traits that make aliens successful is crucial for predicting and preventing biodiversity loss. Pathogens may play an important role in the invasive process, facilitating colonization of their hosts in new continents and islands. According to the Novel Weapon Hypothesis, colonizers may out-compete local native species by bringing with them novel pathogens to which native species are not adapted. In contrast, the Enemy Release Hypothesis suggests that flourishing colonizers are successful because they have left their pathogens behind. To assess the role of avian malaria and related haemosporidian parasites in the global spread of a common invasive bird, we examined the prevalence and genetic diversity of haemosporidian parasites (order Haemosporida, genera Plasmodium and Haemoproteus) infecting house sparrows (Passer domesticus). We sampled house sparrows (N = 1820) from 58 locations on 6 continents. All the samples were tested using PCR-based methods; blood films from the PCR-positive birds were examined microscopically to identify parasite species. The results show that haemosporidian parasites in the house sparrows' native range are replaced by species from local host-generalist parasite fauna in the alien environments of North and South America. Furthermore, sparrows in colonized regions displayed a lower diversity and prevalence of parasite infections. Because the house sparrow lost its native parasites when colonizing the American continents, the release from these natural enemies may have facilitated its invasion in the last two centuries. Our findings therefore reject the Novel Weapon Hypothesis and are concordant with the Enemy Release Hypothesis

Data from: Links between blood parasites, blood chemistry, and the survival probability of nestling American crows

1. Many studies have used the avian haemosporidians (Leucocytozoon, Plasmodium, and Haemoproteus) to test hypotheses of host-parasite co-evolution, yet documented health and survival consequences of these blood parasites vary among studies and generalizations about their pathogenicity are debatable. In general, the negative effects of the haemosporidians are likely to be greatest during acute infections of young birds, yet most previous studies in wild passerines have examined chronic effects in adults. 2. Here, we evaluated responses of nestling American crows (Corvus brachyrhynchos) to acute infection (prevalence and burden), as well as its short- and long-term survival consequences. 3. We used panel of nine hematological and biochemical parameters that are regularly used to evaluate the health of domestic animals, including leukocyte profiles, hematocrit, and plasma proteins. We assessed the effects of infection on survival in a mark-recapture framework. 4. Overall, 56% of crows (n = 321 samples) were infected by at least one of the three genera. Infections by all genera were associated with elevated plasma proteins and globulins, which could indicate an adaptive immune response. However, only Plasmodium infections were associated with low hematocrit (anemia) and lower fledging success, possibly mediated by the negative effect of low hematocrit values on body condition. Moreover, early Plasmodium infection (< 40 days of age) had long-term survival implications: it was associated with lower apparent survival probability within three years after fledging. 5. These results suggest that young crows mounted an adaptive immune response to all three genera. Short- and long-term pathological effects, however, were only apparent with Plasmodium infections

NESTED CYTOCHROME B POLYMERASE CHAIN REACTION DIAGNOSTICS DETECT SPOROZOITES OF HEMOSPORIDIAN PARASITES IN PERIPHERAL BLOOD OF NATURALLY INFECTED BIRDS

ABSTRACT: Some discrepancies between microscopy and PCR-based methods have been recently recorded in the diagnosis of Leucocytozoon spp. infection in naturally infected birds. To clarify this issue, blood samples from 109 yellow-whiskered greenbuls Andropadus latirostris were investigated using both the microscopic examination of blood films and a nested mitochondrial cytochrome b PCR. The overall prevalence of Leucocytozoon spp. infection was 4% after the standard microscopic examination and 17% using the PCR diagnostics. Samples from 9 randomly chosen birds that were microscopy negative, but PCR positive, were then examined microscopically by screening 2 entire blood films from each individual bird. Sporozoites of Leucocytozoon spp. were observed in 4 birds, and 1 gametocyte of the parasite was seen in each of 2 birds. We conclude that sensitive PCR-based diagnostics are able to detect extremely light parasitemias of circulating sporozoites and gametocytes of hemosporidian parasites. Because of the PCR detection of sporozoites of unknown fate in the peripheral circulation, conclusions regarding the distribution of hemosporidian lineages in wildlife should be made with caution. To be accepted as the lineages of successfully developing species of hemosporidians, such PCR-based information should be supported with the detection of blood stages of the parasites. The present study emphasizes the crucial need for a synthesis of information provided by the tools of traditional parasitology and molecular biology, particularly in field studies of blood parasites

BLOOD AND INTESTINAL PARASITES IN WILD PSITTACIFORMES: A CASE STUDY OF BURROWING PARROTS (CYANOLISEUS PATAGONUS)

Masello J, Choconi RG, Sehgal RNM, Tell L, Quillfeldt P. BLOOD AND INTESTINAL PARASITES IN WILD PSITTACIFORMES: A CASE STUDY OF BURROWING PARROTS (CYANOLISEUS PATAGONUS). ORNITOLOGIA NEOTROPICAL . 2006;17(4):515–529.Quantifying parasites is essential for understanding the ecological and evolutionary implica- tions of parasites on their hosts. It is also crucial for many conservation attempts carried out in endan- gered groups of birds, like the Psittaciformes. The aim of the present study was to test for the presence of blood and intestinal parasites of Burrowing Parrots (Cyanoliseus patagonus) (Psittaciformes) breeding in a large colony at the Atlantic coast of Patagonia, Argentina. Although Burrowing Parrots in this colony have several blood-sucking ectoparasites, no blood parasite was detected in blood smears or with the use of a PCR detection method. Likewise, faecal samples of Burrowing Parrots contained no eggs or oocysts of intestinal parasites. We also review the literature on blood and intestinal parasites in wild Psittaciformes, showing that blood parasites were absent in all cases, and 20 out of 28 studies were negative for intestinal parasites. The observed apparent absence of blood parasites in Burrowing Parrots and other Neotropical Psittaciformes is in line with the theory that avian hemosporidians could have been evolved in the tropics of the Old World, where they are widely distributed and prevalent, and they probably penetrated to Central and South America through the Nearctic region of the Holarctic recently. The observed apparent absence of blood parasites could also be explained by innate immunity in Psittaciformes, as has recently been sug- gested for other long-lived bir

Blood Parasites in Owls with Conservation Implications for the Spotted Owl (\u3ci\u3eStrix occidentalis\u3c/i\u3e)

The three subspecies of Spotted Owl (Northern, Strix occidentalis caurina; California, S. o. occidentalis; and Mexican, S. o. lucida) are all threatened by habitat loss and range expansion of the Barred Owl (S. varia). An unaddressed threat is whether Barred Owls could be a source of novel strains of disease such as avian malaria (Plasmodium spp.) or other blood parasites potentially harmful for Spotted Owls. Although Barred Owls commonly harbor Plasmodium infections, these parasites have not been documented in the Spotted Owl. We screened 111 Spotted Owls, 44 Barred Owls, and 387 owls of nine other species for haemosporidian parasites (Leucocytozoon, Plasmodium, and Haemoproteus spp.). California Spotted Owls had the greatest number of simultaneous multi-species infections (44%). Additionally, sequencing results revealed that the Northern and California Spotted Owl subspecies together had the highest number of Leucocytozoon parasite lineages (n = 17) and unique lineages (n = 12). This high level of sequence diversity is significant because only one Leucocytozoon species (L. danilewskyi) has been accepted as valid among all owls, suggesting that L. danilewskyi is a cryptic species. Furthermore, a Plasmodium parasite was documented in a Northern Spotted Owl for the first time. West Coast Barred Owls had a lower prevalence of infection (15%) when compared to sympatric Spotted Owls (S. o. caurina 52%, S. o. occidentalis 79%) and Barred Owls from the historic range (61%). Consequently, Barred Owls on the West Coast may have a competitive advantage over the potentially immune compromised Spotted Owls