In any life stage, lice are treatable with insecticide and perhaps oral medications. The veterinarian will guide treatment depending on the degree of infestation, and the age and health of the bird. Do not try to treat your bird without veterinary help. Many over the counter insect treatments are ineffective or even dangerous. Also, some cases of feather lice may need specialized, supportive care beyond the basic insect treatment. For example, in young birds, anemia or even death can occur if the species victimizing your bird is a blood sucking parasite.
Feather lice are ectoparasites, parasites that live outside of their hosts. In the case of birds, feather lice can survive on the skin and feathers of birds for 2-3 months. Without treatment from a veterinarian, a feather lice infestation can become dangerous, particularly in the case of young birds, or those with underlying health problems. Some species of bird lice are blood sucking, and can cause severe anemia (blood loss) and even death in compromised birds. Birds may potentially have allergic responses to parasites, which can be dangerous, for example, if respiratory in nature.
The veterinarian will diagnose a parasite through physical examination, and the presence of the parasite. Diagnosis is helped along by the usage of a magnification device. An otoscope may be suitable for this purpose. The clinical signs will most likely be evident; the presence of the lice on the wing, ragged moth eaten feathers, and the constant itching that your bird will be experiencing may point to the diagnosis in rapid fashion.
Make sure only to use veterinary-approved treatment and cleaning products, and learn how often reapplication should occur, if necessary. Oftentimes, products found in stores can be harmful, if not fatal for pets. Never use human lice treatments on your birds or animals. Your veterinarian may want to see your bird in a few days to a week after treatment to ensure that the lice have been eradicated.
A study of the genetic heritage of avian feather lice indicates that their louse ancestors first colonized a particular group of birds (ducks or songbirds, for example) and then "radiated" to different habitats on those birds -- to the wings or heads, for instance, where they evolved into different species. This finding surprised the researchers because wing lice from many types of birds look more similar to one another than they do to head or body lice living on the same birds.
Wing lice are long and narrow and insert themselves between the feather barbs of a bird's wings. This allows them to avoid being crushed or removed by a bird when it preens, said Kevin Johnson, a University of Illinois ornithologist with the state Natural History Survey. Johnson conducted the new analysis with Vincent Smith, of the Natural History Museum in London, and Illinois graduate student Scott Shreve.
"If you were just guessing at their ancestry based on external traits, you would think the wing lice on different birds were more closely related to one another than they were to head or body lice on the same bird," Johnson said. "But that's just not the case."
Each type of louse is adapted to life on a particular part of the body. Head lice are rounder than wing lice, for example, and have triangular, grooved heads. The groove helps them cling to a single feather barb so their bird host can't scratch them off.
Body lice are plump and will burrow into the downy feathers or drop from feather to feather to avoid being preened. And the lice known as generalists, which range all over the bird, have their own method of escaping preening: They run.
"The similarities between the lice living in specific habitats on the bodies of birds are really striking," Johnson said. "But it appears that those similarities are the result of what we call 'convergent evolution': The lice independently arrived at the same, or similar, solutions to common ecological problems. This occurred only after they had colonized a particular type of bird."
The two trees looked significantly different from one another, Johnson said. The genetic tree showed that different types of feather lice living on the same type of bird were often closely related, whereas lice that had evolved to survive on specific bird parts, such as the wing, were only distantly related across bird groups, he said.
Ectoparasites such as louse flies (Diptera: Hippoboscidae) have tendency for host specialization, which is driven by adaptation to host biology as well as competition avoidance between parasites of the same host. However, some louse fly species, especially in genera attacking birds, show wide range of suitable hosts. In the presented study, we have surveyed the current status of bird specific louse flies in Finland to provide comprehensive host association data to analyse the ecological requirements of the generalist species. A thorough sampling of 9342 birds, representing 134 species, recovered 576 specimens of louse flies, belonging to six species: Crataerina hirundinis, C. pallida, Ornithomya avicularia, O. chloropus, O. fringillina and Ornithophila metallica. Despite some overlapping hosts, the three Ornithomya species showed a notable pattern in their host preference, which was influenced not only by the host size but also by the habitat and host breeding strategy. We also provide DNA barcodes for ten Finnish species of Hippoboscidae, which can be used as a resource for species identification as well as metabarcoding studies in the future.
(A) Examples of different louse flies in Finnish fauna. Top row: bird louse flies Ornithomya avicularia, O. chloropus and common swift louse fly Crataerina pallida (note the vestigial wings). Lower row: deer ked Lipoptena cervi, batflies Nycteribia kolenatii and Penicillidia monoceros. All images in scale, scale bar 1 mm. (B) Host associations among the three Ornithomya species. Only one Ornithophila metallica was found in this study and Crataerina spp. were collected from their specific hosts, as indicated in the results. (C) Neighbor-Joining tree for the species covered in this study. Note that the tree demonstrates sequence differences between the taxa and does not represent actual phylogeny. The barcode index number (BIN) for each taxon on the right margin.
Louse fly data for the study was obtained via routine ringing of birds at different ringing stations or by local ringers, covering most of Finland (S1 Fig). The permits to catch and ring birds were issued by the Centre for Economic Development, Transport and the Environment (decision number: VARELY/3622/2017) and by the Finnish Wildlife Agency (decision number: 2018-5-600-01158-5). The data consisted two types of information: i) information if a bird has had bird fly or not and ii) information what bird fly species certain bird species had been carrying.
The louse flies included in the study were determined using the relevant literature and identification keys [16, 17]. The COI DNA barcode region was sequenced from one to three specimens of each of the six bird louse flies collected in this study, together with other louse fly specimens, representing all but two species found from Finland (Table 1). The missing species were the sheep ked (Melophagus ovinus (L.)), a species that is probably close to extinction in Finland due to improved animal husbandry and veterinary practises, and the osprey specialist Olfersia fumipennis. DNA sequencing of the standard DNA barcode fragment of mitochondrial COI gene was carried out within the framework of the national campaign of Finnish Barcode of Life ( ). DNA sequencing was conducted in the Centre for Biodiversity Genomics (CGB) at the University of Guelph, Canada, following protocols outlined in deWaard et al. . Briefly, DNA was isolated from the left middle leg of the specimen and the 658bp 5region of the mitochondrial COI gene was amplified with LepF1 and LepR1  primers. Obtained PCR product was column purified and Sanger sequenced. Details of the used DNA extraction, PCR and sequencing vary due to the continuous development of the protocols of CGB, but are provided for each specimens in their sequence page and LIMS report of the Barcode of Life Data Systems (BOLD; ). All collection, taxonomic and sequence data as well as specimen photographs were deposited in the BOLD database and are available through the public dataset of DS-FINHIPPO at dx.doi.org/10.5883/DS-FINHIPPO, including GenBank accession numbers. Calculation of sequence divergences were conducted under Kimura 2-parameter model for nucleotide substitution and with BOLD alignment using BOLD Barcode Gap analysis tool. A Neighbor-Joining tree was built similarly under Kimura 2-parameter model in BOLD and modified with CorelDRAW 2020.
To investigate which factors affect the abundance of bird flies in different species, we build Generalized Linear Mixed Model (GLMM) with Poisson distribution. The response variable was number of bird flies in a given bird individual. The explanatory variables were age of bird (1 = adult, 0 = unknown, -1 young), time period when the sampling was done (see the classification of the four time periods above), latitude coordinate of the record, breeding habitat class, migration strategy, nest site of the host and was the host predator or not (diet). Body size of birds was strongly correlated with the diet and was thus not included to the model. Timing and latitude were included to capture spatio-temporal variation in the abundance of flies. Age of the bird was included as e.g. body condition and timing of migration can differ between age groups [22, 23]. Breeding habitat and nest site of species was included as flies may prefer certain locations to find their hosts. The habitat classes were i) farmland, ii) forest, iii) mires and mountains, iv) scrubland and v) wetland according to Väisänen et al. . The nest site classes of species were i) on land, ii) openly on trees or iii) on cavities according to Cramp et al. . The reader should note that the birds were not necessarily sampled in their breeding habitats but also during the migration when the habitat type of the sampling site can differ from the breeding class. Migratory behaviour has earlier been found to affect many life-history processes of birds, such as abundance changes and moulting [23, 26]. The migration strategy classes of species were i) resident, ii) short-distance migrant (wintering mainly in Europe or Mediterranean) and iii) long-distance migrant (wintering in tropical areas) according to Saurola et al.  and Valkama et al. . We used the diet as a variable because we expected that predator species would have higher number of flies, which may have been received from the prey species. Hawks and owls were classified as predators. Latitudes of the sampling sites were centred before analyses. The explanatory variables did not show any clear collinearity (pearson correlation, r 041b061a72