Influence of bill and foot morphology on the ectoparasites of barn owls

Preening is the principle behavioral defense used by birds to combat ectoparasites. Most birds have a small overhang at the tip of their bills that is used to shear through the tough cuticle of ectoparasitic arthropods, making preening much more efficient. Birds may also scratch with their feet to defend against ectoparasites. This is particularly important for removing ectoparasites on the head, which birds cannot preen. Scratching may be enhanced by the comb-like serrations that are found on the claws of birds in many avian families. We examined the prevalence and intensity of ectoparasites of barn owls (Tyto alba pratincola) in southern Idaho in relation to bill hook length and morphological characteristics of the pectinate claw. The barn owls in our study were infested with 3 species of lice (Phthiraptera: Ischnocera): Colpocephalum turbinatum , Kurodaia subpachygaster, and Strigiphilus aitkeni . Bill hook length was associated with the prevalence of these lice. Owls with longer hooks were more likely to be infested with lice. Conventional wisdom suggests that the bill morphology of raptors has been shaped by selection for efficient foraging; our data suggest that hook morphology may also play a role in ectoparasite defense. The number of teeth on the pectinate claw was also associated with the prevalence of lice. Owls that had claws with more teeth were less likely to be infested with lice, which suggests that larger pectinate claws may offer relatively more protection against ectoparasitic lice. Experiments that manipulate the bill hook and pectinate claw are needed to confirm whether these host characters are involved in ectoparasite defense. Finally, we recovered mammalian ectoparasites from 4 barn owls. We recovered species of mammalian lice (Phthiraptera:Anoplura) and fleas (Siphonaptera) that are commonly found on microtine rodents. The owls probably acquired these parasites from recently eaten prey. This represents 1 of the few documented cases of parasites "straggling" from prey to predator.     

Health of an ex situ population of raptors (Falconiformes and Strigiformes) in Mexico: diagnosis of internal parasites

Successful programs for ex situ and in situ conservation and management of raptors require detailed knowledge about their pathogens. The purpose of this study was to identify the internal parasites of some captive raptors in Mexico, as well as to verify their impact in the health status of infected birds. Birds of prey were confiscated and kept in captivity at the Centro de Investigación y Conservación de Vida Silvestre (CIVS) in Los Reyes La Paz, Mexico State. For this, fecal and blood samples from 74 birds of prey (66 Falconiformes and eight Strigiformes) of 15 species, juveniles and adults from both sexes (39 males and 35 female), were examined for the presence of gastrointestinal and blood parasites. Besides, the oropharyngeal cavity was macroscopically examined for the presence of lesions compatible with trichomoniasis. Among our results we found that lesions compatible with Trichomonas gallinae infection were detected only in two Red-tailed hawks (Buteo jamaicensis) (2.7%); nevertheless, infected birds were in good physical condition. Overall, gastrointestinal parasites were found in 10 (13.5%) raptors: nine falconiforms (13.6%) and one strigiform (12.5%), which mainly presented a single type of gastrointestinal parasite (90%). Eimeria spp. was detected in Harris's hawk (Parabuteo unicinctus), Swainson's hawk (Buteo swainsoni), Red-tailed hawk (B. jamaicensis) and Great horned owl (Bubo virginianus); whereas trematodes eggs were found in Peregrine falcon (Falco peregrinus) and Swainson's hawk (B. swainsoni). Furthermore, eggs of Capillaria spp. were found in one Swainson's hawk (B. swainsoni), which was also infected by trematodes. Hemoprotozoarian were detected in five (6.7%) falconiforms: Haemoproteus spp. in American kestrel (F. sparverius) and Leucocytozoon spp. in Red-tailed hawk (B. jamaicencis). Despite this, no clinical signs referable to gastrointestinal or blood parasite infection were observed in any birds. All parasites identified were recorded for the first time in raptors from Mexico. Furthermore, this represents the first report for T. gallinae, trematodes, Haemoproteus spp. and Leucocytozoon spp. in raptors from Latin America. Diagnosis and control of parasitic infections should be a part of the routine in health care evaluations for ex situ raptor populations. Finally, this information is also valuable for in situ conservation actions on these birds.     

Independent origins of the feather lice (Insecta: Degeeriella) of raptors

Although diurnal birds of prey have historically been placed in a single order due to a number of morphological characters, recent molecular phylogenies have suggested that this is a case of convergence rather than homology, with hawks (Accipitridae) and falcons (Falconidae) forming two distantly related groups within birds. The feather lice of birds have often been used as a model for comparing host and parasite phylogenies, and in some cases there is significant congruence between the two. Thus, studying the phylogeny of the lice of diurnal raptors may be of particular interest with respect to the independent evolution of hawks vs. falcons. Using one mitochondrial gene and three nuclear genes, we inferred a phylogeny for the feather louse genus Degeeriella (which are all obligate raptor ectoparasites) and related genera. This phylogeny indicated that Degeeriella is polyphyletic, with lice from falcons vs. hawks forming two distinct clades. Falcon lice were sister to lice from African woodpeckers, whereas Capraiella, a genus of lice from rollers lice, was embedded within Degeeriella from hawks. This phylogeny showed significant geographical structure, with host geography playing a larger role than host taxonomy in explaining louse phylogeny, particularly within clades of closely related lice. However, the louse phylogeny does reflect host phylogeny at a broad scale; for example, lice from the hawk genus Accipiter form a distinct clade. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 837–847.     

How effective is preening against mobile ectoparasites? An experimental test with pigeons and hippoboscid flies

Birds combat ectoparasites with many defences but the first line of defence is grooming behaviour, which includes preening with the bill and scratching with the feet. Preening has been shown to be very effective against ectoparasites. However, most tests have been with feather lice, which are relatively slow moving. Less is known about the effectiveness of preening as a defence against more mobile and evasive ectoparasites such as hippoboscid flies. Hippoboscids, which feed on blood, have direct effects on the host such asanaemia, as well as indirect effects as vectors of pathogens. Hence, effective defence against hippoboscid flies is important. We used captive Rock Pigeons (Columba livia) to test whether preening behaviour helps to control pigeon flies (Pseudolynchia canariensis). We found that pigeons responded to fly infestation by preening twice as much as pigeons without flies. Preening birds killed twice as many flies over the course of our week-long experiment as birds with impaired preening; however, preening did not kill all of the flies. We also tested the role of the bill overhang, which is critical for effective preening against feather lice, by experimentally removing the overhang and re-measuring the effectiveness of preening against flies. Birds without overhangs were as effective at controlling flies as were birds with overhangs. Overall, we found that preening is effective against mobile hippoboscid flies, yet it does not eliminate them. We discuss the potential impact of preening on the transmission dynamics of blood parasites vectored by hippoboscid flies.     

Tick infestation on birds in an urban Atlantic Forest fragment in north-eastern Brazil

Birds are important hosts for various tick species, playing a significant role in their biological life cycle and dispersion. In this study, we investigated tick infestations on birds trapped in an urban remnant of Atlantic Forest in Pernambuco state, Brazil. From February 2015 to March 2017, 541 birds belonging to 52 species were trapped with mist nets and examined for ectoparasites. Birds trapped in the late successional forest were significantly more infested than birds trapped in the early successional forest. In the same way, ectoparasite infestation varied significantly according to bird weight and collection plot. Overall, 198 birds (36.6%) belonging to 27 species were parasitized by ectoparasites (i.e., ticks, lice and/or mites). Ectoparasites were effectively collected from 111 birds, of which 99 belonging to 20 species were infested by ticks (n?=?261), namely, Amblyomma longirostre (13 nymphs), Amblyomma nodosum (21 nymphs), Amblyomma varium (one nymph), and Amblyomma spp. (five nymphs and 221 larvae). Most of the ticks (>?90%) were collected from Passeriformes. This study provides the second record of A. varium in Pernambuco state and confirms that birds, especially Passeriformes, are important hosts for larvae and nymphs of Amblyomma spp. in the Atlantic Forest biome of Pernambuco.

     

Food partitioning between breeding White-tailed Kites (Elanus leucurus; Aves; Accipitridae) and Barn Owls (Tyto alba; Aves; Tytonidae) in southern Brazil.

I examined the diet of breeding White-tailed Kites (Elanus leucurus; Aves; Accipitridae) and Barn Owls (Tyto alba; Aves; Tytonidae) in an agrarian area of southern Brazil by analyzing regurgitated prey remains. The objective was to evaluate how these raptors, which differ markedly in their hunting activity periods (owls are nocturnal and kites diurnal), share their mammalian food component. 2,087 prey consumed by Barn Owls and 1,276 by White-tailed Kites were identified. They presented a high overlap of food-niches (Piankas index was 0.98). Based on the daily activity period of their main small mammal prey, a lower overlap would be expected. The crepuscular/nocturnal Mus musculus was the main prey for the diet of breeding Barn Owls (81%) and White-tailed Kites (63%). This small exotic rodent provided 63% of the small mammal biomass ingested by owls and 44% by kites. Larger native small mammals were also considered important for the diet of kites, mainly because of their biomass contribution. Although these raptors differ markedly in their hunting activity periods, Barn Owls and White-tailed Kites are very similar predators in southern Brazil, overlapping their diets.     

Ectoparasites of rodents of the urban region of Belo Horizonte, MG. I. Interaction between ectoparasites and hosts

A rodent ectoparasite survey was made in the city of Belo Horizonte, Minas Gerais, Brazil, from June 1980 to September 1982. The species of ectoparasites captured from 950 Rattus norvegicus norvegicus were: Xenopsylla cheopis, Ctenocephalides felis felis, Polyplax spinulosa, Laelaps nuttalli, Echinolaelaps echidninus and Atricholaelaps glasgowi, the last species only represented by three specimens interchanged with wild rodent. P. spinulosa and L. nuttalli, although cosmopolitan, are recorded for the first time in State of Minas Gerais. The sex ratio of the ectoparasites, as well as the prevalence of fleas, mites and lice on the separate sexes of rodents are presented. 66.9% of the rats were infested by mites, almost twice more than infestations by fleas and louse jointly (39%). L. nuttalli was found in great numbers and presented the highest index of infestation: 55.1%. Single infestations are as common as associated ones. P. spinulosa, contrary to L. nuttalli, rarely occurs in single infestation. Data on the distribution of the ectoparasites on the rodents are also reported. The infestation observed in Belo Horizonte is confronted with those obtained by other authors in different places.     

Serological and parasitological prevalence of Toxoplasma gondii in wild birds from Colorado

Ground-feeding birds are considered important in the epidemiology of Toxoplasma gondii because they serve as indicators of soil contamination by oocysts, and birds of prey are indicators of T. gondii prevalence in rodents and other small mammals. Cats excrete environmentally resistant oocysts after consuming tissues of T. gondii -infected birds. In the present study, sera and tissues from 382 wild birds from Colorado were tested for T. gondii infection. Antibodies to T. gondii were found in 38 birds with the use of the modified agglutination test (MAT, 1∶25 titer). Tissues (brains, hearts) of 84 birds were bioassayed in mice. Viable T. gondii was isolated from 1 of 1 barn owl (Tyto alba), 1 of 5 American kestrels (Falco sparverius), 1 of 7 ferruginous hawks (Buteo regalis), 1 of 4 rough-legged hawks (Buteo lagopus), 2 of 13 Swainson's hawks (Buteo swainsoni), and 1 of 25 red-tailed hawks (Buteo jamaicensis). This is the first time T. gondii has been isolated from the barn owl, ferruginous hawk, rough-legged hawk, and Swainson's hawk.     

The inventory of coot (Fulica amra) ectoparasites in the north-west of Algeria

The inventory of coot (Fulico atra) ectoparasites during wintering season (October 2004-March 2005) has been carried out from 17 individuals captured in lake Tonga. Results show that mites are the most abundant parasites (65.6%), followed by lice (Pseudomenopon pilosum, Rallicolo fulicae, Fullicofulo lurida, Incidifrons fulicae, Laemobothrion atrum) 34.4% and leeches (Theromyzone sp) with 0.05%. All individuals were infested with lice, 82.4% with mites and 41.2% with leeches.     

Impact of feather molt on ectoparasites: looks can be deceiving

Animals possess a variety of well-documented defenses against ectoparasites, including morphological, behavioral, and immune responses. Another possible defense that has received relatively little attention is the shedding of the host's exterior. The conventional wisdom is that ectoparasite abundance is reduced when birds molt their feathers, mammals molt their hair, and reptiles shed their skin. We carried out an experimental test of this hypothesis for birds by manipulating molt in feral pigeons (Columba livia) infested with feather lice (Phthiraptera: Ischnocera). We used two standard methods, visual examination and body washing, to quantify the abundance of lice on the birds. The visual data indicated a significant effect of molt on lice. However, the more robust body washing method showed that molt had no effect on louse abundance. Two factors caused visual examination to underestimate the number of lice on molting birds. First, molt replaces worn feathers with new, lush plumage that obscures lice during visual examination. Second, we discovered that lice actively seek refuge inside the sheath that encases developing feathers, where the lice cannot be seen. The apparent reduction in louse abundance caused by these factors may account for the conventional wisdom that feather molt reduces ectoparasite abundance in birds. In light of our experimental results, we argue that it is necessary to reinterpret the conclusions of previous studies that were based on observational data. Additional experiments are needed to test whether shedding of the host's exterior reduces ectoparasites in other birds, mammals, and reptiles, similar to the impact of facultative leaf drop on herbivorous insects on trees.

     

Horizontal and vertical ectoparasite transmission of three species of Malophaga, and individual variation in european bee-eaters (Merops apiaster)

Dispersal of avian ectoparasites can occur through either vertical transmission from adult birds to their offspring in the nest or through horizontal transmission between adult birds or through phoresy. In this study, we investigated the importance of the 2 main transmission modes in the colonial European bee-eater and examined whether individual differences in ectoparasite intensity exist in relation to age, sex, and morphological features of the birds. The intensity of 3 chewing lice species was investigated. Almost all adult bee-eaters (98.3%, n = 176) were infested with 1 of the 3 ectoparasite species, whereas only 10.8% (n = 167) of all chicks were infested. Meropoecus meropis was the most frequent ectoparasite species on adult bee-eaters (prevalence 94.3%), whereas Meromenopon meropis was the most common species on chicks (prevalence 9.6%). Our results suggest that chewing lice are mainly horizontally transmitted among adult bee-eaters and mainly among pair members, whereas vertical transmission between parents and nestlings is less frequent. These conclusions were supported by a relation in ectoparasite intensity of pair members and a parasite removal experiment. Ectoparasite intensity was in general low in nestlings and did not correlate with ectoparasite intensity of their parents. Host age, sex, weight, and other morphological features did not explain variation in chewing lice infestation.     

Frequency and consequences of feather holes in Barn Swallows Hirundo rustica

The relationship between feather quality, estimated through the prevalence and intensity of feather holes, and the breeding performance and survival of the Barn Swallow Hirundo rustica was studied over a 5-year period. In addition, we present some indirect data on the role of chewing lice in producing the feather holes. The balanced distribution of feather holes (high prevalence, low aggregation) corresponds with the pattern of distribution of lice on colonial birds, and in the Barn Swallow. Feather holes were significantly and positively associated with the arrival dates of the birds, as both males and females with an increased number of feather holes started laying later. Females that survived the winter had significantly fewer holes than non-surviving females, whereas there was no difference in feather hole number between surviving and non-surviving males. Given that there was no association between the number of feather holes and body condition indices, except for the tail length of male Barn Swallows, we suggest that the negative effect of feather holes on the fitness of the birds is mainly apparent during periods of intensive locomotor activity, such as migration. Alternatively, if feather holes are an indicator of quality, those birds with a high intensity of feather holes may have been of poor quality. These birds may have been less able to cope with the environmental conditions, resulting in the lower survival and later arrival of the birds to the breeding grounds. The negative relationship between the length of the outermost tail feathers of males and the incidence of feather holes suggests that the tail is a condition-dependent secondary sexual characteristic.     

Seasonal variation of infestation by ectoparasitic chigger mite larvae (Acarina: Trombiculidae) on resident and migratory birds in coffee agroecosystems of Chiapas, Mexico

Parasitism is not well documented for birds found in tropical habitats. Long-distance migratory birds may face additional risks to an already hazardous journey when infected. This study explores the ecology of an ectoparasite infestation in Chiapas, Mexico. During a mist-netting project in 2 different coffee management systems, chigger mites (Acarina: Trombiculidae), ectoparasitic during the larval stage, were found on both resident and migratory birds. Using a rapid assessment protocol, it was observed that 17 of 26 species of long-distance migrants and 33 of 71 resident species had at least 1 infested individual. Infestation prevalences were unexpectedly high on some long-distance migrants, as high as 0.73 for Swainson's thrush (Catharus ustulatus), a value on par with heavily infested resident species. Prevalence was highest during winter sampling: 0.18 overall, 0.16 of migrants, and 0.23 of residents. Prevalence was 0.14 for resident birds during the summer breeding season. Mean abundance and mean intensity of infestation are reported for 97 species captured and inspected during the course of this study. In this region, chigger mite larvae are relatively common on birds and their abundance varies seasonally. High prevalence for some migratory birds suggests that more research and monitoring of ectoparasites are needed, especially in light of emerging diseases.     

Occurrence of mycoplasmas in free-ranging birds of prey in Germany

Mycoplasmas are well-known avian pathogens of poultry and some passerines. Although reported in birds of prey, their role as pathogens is still unclear. Healthy, free-ranging raptor nestlings sampled during a routine ringing (banding) program, and birds of prey from rehabilitation centers, tested positive for Mycoplasma spp. by culture and a genus-specific polymerase chain reaction (PCR). Given the lack of clinical signs and disease, we suggest that mycoplasmas in raptors may be commensal rather than pathogenic. Using immunobinding assay and species-specific PCR tests, Mycoplasma buteonis, M. falconis, and M. gypis were identified; M. falconis was only detected in falcons. Additionally, some isolates could not be identified. This is the first report of Mycoplasma spp. isolations from Western Marsh Harriers (Circus aeroginosus), a Eurasian Hobby (Falco subbuteo), and a Barn Owl (Tyto alba).     

A new species of parasitic mites of the genus Syringophiloidus Kethley 1970 (Acari: Syringophilidae) from the barn swallow Hirundo rustica Linnaeus, 1758

A new quill mite species Syringophiloidus hirundinis (Acari: Syringophilidae) is described from the Barn Swallow Hirundo rustica. The species Syringophiloidus hirundinis had a prevalence of 17.1% in the two outermost tail feathers (N = 208 adult Barn Swallows) during the breeding season of the Barn Swallow host. Intensity of infestation was 9.7 adult mites per pair of infested tail feathers. The sex ratio was highly biased towards females, with only 7.5% of all individuals being males (20:3).     

Comprehensive investigation of ectoparasite community and abundance across life history stages of avian host

Fitness consequences of ectoparasitism are expressed over the lifetime of their hosts in relation to variation in composition and abundance of the entire ectoparasite community and across all host life history stages. However, most empirical studies have focused on parasite species-specific effects and only during some life history stages. We conducted a systematic, year-long survey of an ectoparasite community in a wild population of house finches Carpodacus mexicanus Müller in south-western Arizona, with a specific focus on ecological and behavioral correlates of ectoparasite prevalence and abundance. We investigated five ectoparasite species: two feather mite genera – both novel for house finches – Strelkoviacarus (Analgidae) and Dermoglyphus (Dermoglyphidae), the nest mite Pellonyssus reedi (Macronyssidae), and the lice Menacanthus alaudae (Menoponidae) and Ricinus microcephalus (Ricinidae). Mite P. reedi and louse Menacanthus alaudae abundance peaked during host breeding season, especially in older birds, whereas feather mite abundance peaked during molt. Overall, breeding birds had more P. reedi than non-breeders, molting males had greater abundance of feather mites than molting females and non-molting males, and young males had more feather mites than older males. We discuss these results in relation to natural history of ectoparasites under study and suggest that ectoparasites might synchronize their life cycles to those of their hosts. Pronounced differences in relative abundance of ectoparasite species among host's life history stages have important implications for evolution of parasite-specific host defenses.     

Newcastle disease virus and Chlamydia psittaci in free-living raptors from eastern Germany

Organ samples from free-living raptors from the federal states of Berlin and Brandenburg in eastern Germany were tested for Newcastle disease virus (NDV; n = 331) and Chlamydia psittaci (n = 39) by polymerase chain reaction (PCR). In 18 individuals NDV nucleic acids were detected. These samples originated from barn owls (Tyto alba; n = 15, 28%), tawny owl (Strix aluco; n = 1, 5%), common buzzard (Buteo buteo, n = 1, 1%), and European kestrel (Falco tinnunculus; n = 1, 4%). In 29 (74%) of 39 samples C. psittaci was detected. Chlamydia psittaci is common in free-living birds of prey in the investigated area.     

Does sunlight enhance the effectiveness of avian preening for ectoparasite control?

Preening is a bird's first line of defense against harmful ectoparasites. Ectoparasites, in turn, have evolved adaptations for avoiding preening such as hardened exoskeletons and escape behavior. Earlier work suggests that some groups of ectoparasites, such as feather lice, leave hiding places in feathers that are exposed to direct sunlight, making them more vulnerable to preening. It is, therefore, conceivable that birds may choose to preen in direct sunlight, assuming it improves the effectiveness of preening. Using mourning doves and their feather lice, we tested 2 related hypotheses; (1) that birds with access to direct sunlight preen more often than birds in shade, and (2) that birds with access to direct sunlight are more effective at controlling their ectoparasites than birds in shade. To test these hypotheses, we conducted an experiment in which we manipulated both sunlight and preening ability. Our results provided no support for either hypothesis, i.e., birds given the opportunity to preen in direct sunlight did not preen significantly more often, or more effectively, than did birds in shade. Thus, the efficiency of preening for ectoparasite control appears to be independent of light intensity, at least in the case of mourning doves and their feather lice.     

Efficacy of ivermectin (Ivomec) against intestinal capulariosis in falcons

52 captive falcons out of 3,988 (1.3 %) raptors microscopically examined for intestinal parasites in the Middle East proved infested with hairworms (capillariid parasites). 26 of these (50 %) showed concurrent parasitoses. In the group of 26 falcons diagnosed with capillariosis as sole infestation (50 %) compatible clinical signs such as anorexia, weight loss, weakness, dyspnoea, regurgitation of food and blood, diarrhoea and dark tarry faeces, were recorded. These birds were treated intramuscularly with ivermectin at doses of 2 mg/kg. In fecal samples examined 10-15 days later, the eggs of capillariid parasites had disappeared, in association with complete clinical recovery.     

Host-ectoparasite associations; the role of host traits,season and habitat on parasitism interactions of the rodents of northeastern Iran

Rodents play a significant role as reservoirs of zoonotic diseases. Nevertheless, in general their ectoparasite assemblage and host-ectoparasite associations are poorly known. This study intended to provide new insights into the relationships between ectoparasites and rodents in northeastern Iran. Rodents were captured using live traps during the years 2016–2020, and their ectoparasites were collected. Parasitological indices such as infestation rate, prevalence and mean intensity of infestation were analyzed. A total of 284 rodents, belonging to 17 species, were trapped and found to be infested by 178 ectoparasites from five orders Siphonaptera, Phthiraptera, Ixodida, Mesostigmata and Trombidiformes. The overall infestation rate was 50.3%. The flea Nosopsyllus fasciatus and the louse Polyplax asiatica dominated among all fleas and lice, respectively. Haemaphysalis punctata and Haemolaelaps sp. were recorded as the most abundant tick and mite, respectively. Nosopsyllus fasciatus exhibited low and Polyplax asiatica moderate host specificity. Approximately 64.2% of ectoparasites shared more than one host, and others were singletons. Seasonal fluctuations were found in the occurrence of ectoparasite; fleas and lice were more abundant in spring and winter, respectively. Ticks demonstrated high abundance in spring and summer and mites were more common in autumn. The overall prevalence of ectoparasite on male rodents was greater than that on females (56.4% vs. 44.4%), while similar mean intensities were detected for both sexes. This study extends the knowledge on the distribution, seasonality and host choice of four main groups of ectoparasites in association with rodents. Further studies are needed to provide deep insight into how relationships and interactions between ectoparasite and rodents are formed, and how they can be applied in epidemiology.