New Records of Feather Mites (Acariformes: Analgoidea) on Passerines (Aves: Passeriformes) from Greenland

Simple Summary

Feather mites are a highly specialised group of minuscule arthropods that reside primarily on birds’ feathers. Recent studies have shown that they might play an important role in controlling the number of harmful microorganisms on the feathers, therefore being in a mutualistic relationship with the birds. Their high diversity and specialisation make them a good model system for studying co-evolution with their bird hosts. Feather mites are found on all continents, including in the harsh Arctic conditions of Greenland. In this environment, they are protected within the plumage of their warm-blooded hosts. However, the feather mite fauna in the extreme north is poorly known, as the only records in Greenland date back to the beginning of the 20th century. In this study, we report three species of feather mites (Analges longispinosus, Proctophyllodes plectrophenax, and P. hipposideros) from three common species of passerines (Snow Bunting, Lapland Longspur, and Northern Wheatear), two of which represent new records for Greenland. Our results will contribute to the knowledge of this rarely studied group of invertebrates.

Abstract

Feather mites play an important role in bird communities, covering a wide spectrum of associations with their hosts, ranging from parasitic to mutualistic relations. As a result of long co-evolution with their warm-blooded hosts, this diverse group of arthropods can be found in a wide range of environments where their hosts occur, including the high Arctic. The feather mite fauna of Greenland is poorly known. Herein, we present new data on feather mites found on three species of passerine birds, which were captured on Disko Island (Qeqertarsuaq), West Greenland. The feather mite species Analges longispinosus was found on Snow Bunting (Plectrophenax nivalis); Proctophyllodes plectrophenax on Snow Bunting and Lapland Longspur (Calcarius lapponicus); and Proctophyllodes hipposideros on Northern Wheatear (Oenanthe oenanthe). The two Proctophyllodes species represent new records for Greenland. Further studies are needed to reveal the diversity of feather mite species in this remote Arctic region.

1. Introduction

Feather mites are a diverse group of highly specialised obligate symbionts associated with birds [1,2,3]. Most of them inhabit different parts of birds’ plumage, and based on their microhabitat preferences and morphological adaptations, they can be grouped into five different morphoecotypes [4,5]. Previously viewed as parasites on birds, most feather mites are now considered to be in commensal or mutualistic relationships with their avian hosts [3,6,7]. Studies on their gut content have shown that they feed on a variety of microorganisms like fungi, bacteria, as well as other organic particles, in this way cleaning the feathers and possibly removing harmful microorganisms [2,3,8,9].

Due to their low mobility and the need for direct contact between the hosts for transmission to occur, feather mites show a high level of host-specificity [1,10,11]. This makes them a suitable model for studying co-evolution with their hosts and the mechanisms driving their diversification and speciation [1,12]. As a result of long co-evolution with their warm-blooded hosts, a diverse group of feather mites can be found over a wide range of environments where their hosts reside, including the unique environments of the polar regions [13,14]. Ongoing climate change, which is amplified in the Arctic, can have major consequences for the bird population, as some southern species will expand their distribution ranges northwards along with their symbiotic communities [15,16,17]. This might give rise to opportunities for new avian–mite species interactions.

Greenland is almost wholly classified as being in the Arctic, defined as areas in the Northern Hemisphere where at sea level the average temperature during the warmest month does not exceed 10 °C [18,19]. It has a harsh climate with long, cold winters and a short growing season; subsequently, both its fauna and flora are impoverished compared to those of more southern realms [19]. As a result of the last glaciation, most living organisms now found on Greenland are considered to be postglacial immigrants [20]. Birds and mammals that are living on Greenland provide, with their endothermic bodies, a well-protected biotope from the extreme weather for many ectoparasitic invertebrates, including feather mites [19]. However, the low number of host species from most avian orders found in these areas [21] is a prerequisite for a reduced feather mite fauna compared to more temperate regions. Additionally, the remoteness and the harsh climate of the Arctic make it a challenging place for conducting parasitological studies.

The avifauna of Greenland has been studied over the last few centuries, and the bird list has been continuously updated and the references therein [22]. Detailed reports on the natural history of many bird species, including the common passerines, in West Greenland and Disko Island were published by Stone [23] and Longstaff [24]. The current avifauna of Greenland comprises 253 species, most of which are members of the orders Anseriformes and Charadriiformes [21]. The passeriform birds are represented by 76 species, of which only 10 are commonly found in Greenland [21]. With the process of global warming, which makes the distribution ranges of birds move northwards, we are expecting these numbers to rise [25,26].

Disko Island (Qeqertarsuaq) is situated off the west coast of Greenland in Baffin Bay. It is located in the low-Arctic climate zone, just south of the high-Arctic transition zone, and has tundra vegetation, characterised by low shrubs, mosses, and lichens [27,28,29]. Waterfowl, seabirds, and waders mainly represent the breeding avifauna of the island; however, five species of passerines are regular breeders on Disko Island—Snow Bunting (Plectrophenax nivalis), Lapland Longspur (Calcarius lapponicus), Northern Wheatear (Oenanthe oenanthe), Redpoll (Acanthis flammea), and Common Raven (Corvus corax) [27,30].

Feather mites on birds from Greenland are poorly studied, with six species recorded to date by Trägårdh [31]. However, the majority require further studies, as some probably belong to other species [19,32]. One species, Analges longispinosus Tyrrell, 1882, was found on a passerine bird species, Snow Bunting. In addition, in his publication, Trägårdh [31] listed 11 other feather mite species expected to be found on birds commonly occurring in the country.

As part of another study involving bird trapping, we took the opportunity to collect feather mites from three common species of passerine birds, aiming to provide new data on their diversity and distribution in this poorly studied and isolated region.

2. Materials and Methods

We collected feather mites from three bird species—Snow Bunting (n = 22) (Figure 1), Lapland Longspur (n = 7), and Northern Wheatear (n = 23). The birds were captured from 5 to 12 July 2011 with baited clap-net traps in the vicinity of the Arctic Station of the University of Copenhagen, at Qeqertarsuaq, Disko Island (Qeqertarsuaq), Greenland (69°15′ N; 53°31′ W). The catching area was dominated by dense shrubs of various dwarf forms of willow species (Salix spp.) and herbs growing between basalt rocks. The birds were ringed, measured, and subsequently checked for feather mites by examining their feathers under strong sunlight with the naked eye, either directly in the field or indoors.

Mite specimens were collected from the wing feathers while holding the bird in hand, with a needle by Mihaela Ilieva, and stored in tubes with 70% ethanol. The only individual found on an undertail covert feather was collected together with the feather. The feather mites were mounted on microscope slides in Euparal mounting medium and identified by Nevena Kolarova. Species identification was based on Tyrrell [33], Atyeo & Braasch [34], and Mironov [35]. Microscope slides used in the present study were deposited in the Zoological Collection of Sofia University “St. Kliment Ohridski”, Faculty of Biology (BFUS no. BFUS-ACR000037-BFUS-ACR000088). Photographs of feather mites were taken using a combination of a Canon EOS 2000D (Canon, Tokyo, Japan) digital camera and an Olympus BX41 microscope (Olympus, Tokyo, Japan).

3. Results and Discussion

The collected feather mites (n = 399) from three species belonged to two families of the superfamily Analgoidea—Analgidae and Proctophyllodidae.

Family Analgidae

Analges longispinosus Tyrrell, 1882

We collected one male feather mite from this species on a Snow Bunting (collection number BFUS-ACR000053).

Analges longispinosus is a species-specific feather mite for the Snow Bunting [36,37] found on an undertail covert feather. It has been previously reported on this host by Trägårdh [31] for Western Greenland. The species was found on this host in the Novaya Zemlya archipelago (Vitzthum 1924 in [38]) and Wrangel Island [13]. Later, Mironov [35] reported the species from Kaliningrad Oblast and Volgograd Oblast, and Mironov et al. [39] from the Lower Don Area in the European part of Russia.

Family Proctophyllodidae

Proctophyllodes plectrophenax Mironov, 2012

We collected 81 males and 73 females from this species on 21 Snow Buntings (BFUS-ACR000037-BFUS-ACR000058) (Figure 2) and 11 males and 34 females on seven Lapland Longspurs (BFUS-ACR000082-BFUS-ACR000088).

The species was collected from the wing feathers of both bird species. Dubinin [13] collected feather mites from these two bird species on Wrangel Island and identified them as Proctophyllodes megaphyllus. Most probably, this was the species Proctophyllodes plectrophenax, first described by Mironov, since P. megaphyllus is found on birds in the genus Prunella [35]. Apart from the records of Dubinin, Proctophyllodes plectrophenax has been reported from the European part of Russia and Iceland on both hosts [35,39].

Proctophyllodes hipposideros Gaud, 1953

We collected 33 males and 55 females from this species on 23 Northern Wheatears (Figure 3) (BFUS-ACR000059-BFUS-ACR000081).

The species was collected from the wing feathers. It has been found on this host in Europe, Central, and North Africa [34,36].

As described above, all three feather mite species collected during the present study are already known from their respective hosts; however, Proctophyllodes plectrophenax and P. hipposideros represent new records for Greenland. With this, our study adds new data to the circumpolar distribution of the studied feather mite species.

However, we should point out that there are some limitations to our work. Since we collected the feather mites as a side project to another study targeted at the Northern Wheatear, we did not aim to capture a variety of bird species. We also did not have the opportunity to examine fully each bird that was captured, and therefore, we cannot provide data on the prevalence and the intensity of the feather mites on these hosts. Nevertheless, we collected feather mites from three of the four bird species breeding in the study location [27].

In Greenland, the only survey on feather mites was conducted over a century ago [31]. Feather mites have been studied in more detail on another Arctic Island, Wrangel, where Dubinin [13] examined 43 bird species, 14 of which were passerines, and identified 46 species of feather mites on them. In other Arctic areas, such as Iceland and Svalbard, only a few species have been recorded, mostly on seabirds [32,40,41,42]. Further studies, covering the other land bird species in Greenland and the much larger diversity of marine and coastal birds, will be necessary to determine which feather mite species reach the northern limits of their hosts’ distribution.

4. Conclusions

The fauna of Greenland has now been enriched with two new species of feather mites (Proctophyllodes plectrophenax and P. hipposideros), and one species (Analges longispinosus) has been confirmed after more than a century. Future studies are likely to add more species of feather mites to the list of Greenland.