Does allopreening control avian ectoparasites?

Host Migration and Size Do Not Influence the Prevalence of Most Chewing Lice (Phthiraptera: Amblycera and Ischnocera) on Shorebirds (Aves: Charadriiformes) across the World

Patterns of prevalence in chewing lice (Phthiraptera) on wild birds are poorly known, as are the underlying factors that influence these patterns. Here, we analyze a data set consisting of published prevalence data of lice on shorebirds, as well as new prevalence data from shorebirds examined in Australia, Canada, China, Japan, and Sweden between 2007 and 2020. In total, prevalence data from 10 genera of lice from over 110 host species were included, including all major families of shorebirds. Using a generalized linear mixed model, we examine how the prevalence of lice of different genera varies between different sets of birds, focusing on two factors associated with migration (migration length and migration route). We found that host body size does not influence prevalence of lice in the Charadriiformes for any of the four most common and widely distributed louse genera (Actornithophilus, Austromenopon, Quadraceps, and Saemundssonia). Moreover, neither of the two migration variables showed any statistically significant correlations with prevalence, except for the genus Saemundssonia in which the prevalence of lice on short-distance migrants was significantly higher than on intermediate- and long-distance migrants. We also present 15 new records of chewing lice for China and 12 for Australia.

Intimacy across species boundaries: Interspecific allopreening between Spot‐necked ( Stachyris strialata ) and Nonggang Babblers ( S. nonggangensis )

Allopreening occurs in many species of birds and is known for providing hygienic and social benefits. While this behavior has been extensively studied among conspecifics, its occurrence among different species remains little known. Outside of captive environments, only a few records of interspecific allopreening exist. In this study, we describe our observations of the interspecific allopreening behavior between Spot‐necked (Stachyris strialata) and Nonggang Babblers (S. nonggangensis) in a non‐captive environment in southern China. To our knowledge, these observations represent the first record of interspecific allopreening in the family Timaliidae. We suggest that this understudied behavior is most likely related to the dominant–subordinate relationship between these two species: either the dominant species preening the subordinate species to assert dominance or the subordinate species preening the dominant species to reduce tensions by appeasement. We also suggest interspecific allopreening may not be as rare as we thought if we study this behavior under circumstances where different species are close to each other. This study contributes to our understanding of not only the potential mechanism(s) behind interspecific allopreening but also the behavioral ecology of the vulnerable Nonggang Babbler.

Social contact behaviors are associated with infection status for Trichuris sp. in wild vervet monkeys (Chlorocebus pygerythrus)

Social grooming in the animal kingdom is common and serves several functions, from removing ectoparasites to maintaining social bonds between conspecifics. We examined whether time spent grooming with others in a highly social mammal species was associated with infection status for gastrointestinal parasites. Of six parasites detected, one (Trichuris sp.) was associated with social grooming behaviors, but more specifically with direct physical contact with others. Individuals infected with Trichuris sp. spent significantly less time grooming conspecifics than those not infected, and time in direct contact with others was the major predictor of infection status. One model correctly predicted infection status for Trichuris sp. with a reliability of 95.17% overall when the variables used were time spent in direct contact and time spent grooming others. This decrease in time spent grooming and interacting with others is likely a sickness behavior displayed by individuals with less energy or motivation for non-essential behaviors. This study emphasizes the possible links between host behavior and parasitic infections and highlights the need for an understanding of a study population’s parasitic infections when attempting to interpret animal behavior.

Population Dynamics of Chewing Lice (Phthiraptera) Infesting Birds (Aves)

In the past 25 years, studies on interactions between chewing lice and their bird hosts have increased notably. This body of work reveals that sampling of live avian hosts, collection of the lice, and the aggregated distributions of louse infestations pose challenges for assessing louse populations. The number of lice on a bird varies among host taxa, often with host size and social system. Host preening behavior limits louse abundance, depending on bill shape. The small communities of lice (typically one-four species) that live on individual birds show species-specific patterns of abundance, with consistently common and rare species, and lower year-to-year population variability than other groups of insects. Most species of lice appear to breed continuously on their hosts, with seasonal patterns of abundance sometimes related to host reproduction and molting. Competition may have led to spatial partitioning of the host by louse species, but seldom contributes to current patterns of abundance.

Does latitudinal migration represent an advantage in the decrease of ectoparasitic loads in Leptonycteris yerbabuenae (Chiroptera)?

Latitudinal migration increases fitness of migrants by allowing them to exploit favorable conditions in nonadjacent geographic regions. Other consequences also may follow, such as interactions with parasites. Migrants may have lower parasite prevalence and abundance than resident individuals because of their ability to abandon infested areas or due to mortality of highly infested hosts. To further understand whether variation in ectoparasite loads is influenced by migration, we investigated whether prevalence and abundance of two species of obligate ectoparasites, the wing mite Periglischrus paracaligus (Mesostigmata: Spinturnicidae) and the bat fly Nycterophilia coxata (Diptera: Streblidae, Nycterophiliinae), of the lesser long-nosed bat, Leptonycteris yerbabuenae, varied between migratory and resident populations throughout their range in Mexico. We examined the presence or absence of migratory behavior, as well as sex and reproductive status of the host because ectoparasitism differentially affects the sexes. Our results showed that the prevalence of both ectoparasites did not vary between migrant and resident females or males, but abundance of the wing mite P. paracaligus was lower in migrant females compared with resident females, with an important influence from the reproductive status of the host. A partial negative relationship between ectoparasite loads and latitudinal migration therefore was demonstrated.

Elder Barn Owl Nestlings Flexibly Redistribute Parental Food according to Siblings' Need or in Return for Allopreening

Kin selection and reciprocation of biological services are distinct theories invoked to explain the origin and evolutionary maintenance of altruistic and cooperative behaviors. Although these behaviors are not considered to be mutually exclusive, the cost-benefit balance of behaving altruistically or cooperating reciprocally and the conditions promoting a switch between such different strategies have rarely been tested. Here, we examine the association between allofeeding, allopreening, and vocal solicitations in wild barn owl (Tyto alba) broods under different food abundance conditions: natural food provisioning and after an experimental food supplementation. Allofeeding was performed mainly by elder nestlings (hatching is asynchronous) in prime condition, especially when the cost of forgoing a prey was small (when parents allocated more prey to the food donor and after food supplementation). Nestlings preferentially shared food with the siblings that emitted very intense calls, thus potentially increasing indirect fitness benefits, or with the siblings that provided extensive allopreening to the donor, thus possibly promoting direct benefits from reciprocation. Finally, allopreening was mainly directed toward older siblings, perhaps to maximize the probability of being fed in return. Helping behavior among relatives can therefore be driven by both kin selection and direct cooperation, although it is dependent on the contingent environmental conditions.

Anti-parasite behaviour of birds

Birds have many kinds of internal and external parasites, including viruses, bacteria and fungi, as well as protozoa, helminths and arthropods. Because parasites have negative effects on host fitness, selection favours the evolution of anti-parasite defences, many of which involve behaviour. We provide a brief review of anti-parasite behaviours in birds, divided into five major categories: (i) body maintenance, (ii) nest maintenance, (iii) avoidance of parasitized prey, (iv) migration and (v) tolerance. We evaluate the adaptive significance of the different behaviours and note cases in which additional research is particularly needed. We briefly consider the interaction of different behaviours, such as sunning and preening, and how behavioural defences may interact with other forms of defence, such as immune responses. We conclude by suggesting some general questions that need to be addressed concerning the nature of anti-parasite behaviour in birds.This article is part of the Theo Murphy meeting issue 'Evolution of pathogen and parasite avoidance behaviours'.

Phoretic dispersal influences parasite population genetic structure

Dispersal is a fundamental component of the life history of most species. Dispersal influences fitness, population dynamics, gene flow, genetic drift and population genetic structure. Even small differences in dispersal can alter ecological interactions and trigger an evolutionary cascade. Linking such ecological processes with evolutionary patterns is difficult, but can be carried out in the proper comparative context. Here, we investigate how differences in phoretic dispersal influence the population genetic structure of two different parasites of the same host species. We focus on two species of host-specific feather lice (Phthiraptera: Ischnocera) that co-occur on feral rock pigeons (Columba livia). Although these lice are ecologically very similar, "wing lice" (Columbicola columbae) disperse phoretically by "hitchhiking" on pigeon flies (Diptera: Hippoboscidae), while "body lice" (Campanulotes compar) do not. Differences in the phoretic dispersal of these species are thought to underlie observed differences in host specificity, as well as the degree of host-parasite cospeciation. These ecological and macroevolutionary patterns suggest that body lice should exhibit more genetic differentiation than wing lice. We tested this prediction among lice on individual birds and among lice on birds from three pigeon flocks. We found higher levels of genetic differentiation in body lice compared to wing lice at two spatial scales. Our results indicate that differences in phoretic dispersal can explain microevolutionary differences in population genetic structure and are consistent with macroevolutionary differences in the degree of host-parasite cospeciation.

Allopreening in birds is associated with parental cooperation over offspring care and stable pair bonds across years

Individuals of many species form bonds with their breeding partners, yet the mechanisms maintaining these bonds are poorly understood. In birds, allopreening is a conspicuous feature of interactions between breeding partners and has been hypothesized to play a role in strengthening and maintaining pair bonds within and across breeding attempts. Many avian species, however, do not allopreen and the relationship between allopreening and pair bonding across species remains unexplored. In a comparative analysis of allopreening and pair bond behavior, we found that allopreening between breeding partners was more common among species where parents cooperate to rear offspring. The occurrence of allopreening was also associated with an increased likelihood that partners would remain together over successive breeding seasons. However, there was no strong evidence for an association between allopreening and sexual fidelity within seasons or time spent together outside the breeding season. Allopreening between partners was also no more common in colonial or cooperatively breeding species than in solitary species. Analyses of evolutionary transitions indicated that allopreening evolved from an ancestral state of either high parental cooperation or high partner retention, and we discuss possible explanations for this. Overall, our results are consistent with an important role for allopreening in the maintenance of avian pair bonds.

Does allopreening control avian ectoparasites?

For birds, the first line of defence against ectoparasites is preening. The effectiveness of self-preening for ectoparasite control is well known. By contrast, the ectoparasite control function of allopreening-in which one birds preens another-has not been rigorously tested. We infested captive pigeons with identical numbers of parasitic lice, and then compared rates of allopreening to the abundance of lice on the birds over time. We documented a negative relationship between rates of allopreening and the number of lice on birds. Moreover, we found that allopreening was a better predictor of louse abundance than self-preening. Our data suggest that allopreening may be a more important means of ectoparasite defence than self-preening when birds live in groups. Our results have important implications for the evolution of social behaviour.