Rusty Blackbird Research Articles

Climate change and the decline of a once common bird

Climate change is predicted to negatively impact wildlife through a variety of mechanisms including retraction of range. We used data from the North American Breeding Bird Survey and regional and global climate indices to examine the effects of climate change on the breeding distribution of the Rusty Blackbird (Euphagus carolinus), a formerly common species that is rapidly declining. We found that the range of the Rusty Blackbird retracted northward by 143 km since the 1960s and that the probability of local extinction was highest at the southern range margin. Furthermore, we found that the mean breeding latitude of the Rusty Blackbird was significant and positively correlated with the Pacific Decadal Oscillation with a lag of six years. Because the annual distribution of the Rusty Blackbird is affected by annual weather patterns produced by the Pacific Decadal Oscillation, our results support the hypothesis that directional climate change over the past 40 years is contributing to the decline of the Rusty Blackbird. Our study is the first to implicate climate change, acting through range retraction, in a major decline of a formerly common bird species.

Exploratory analysis of correlates of the abundance of rusty blackbirds (Euphagus carolinus) during fall migration

The rusty blackbird (Euphagus carolinus) has received much attention during the last decade, in part due to drastic population declines. We analyzed data from 15 y of fall migration monitoring at the Observatoire d'oiseaux de Tadoussac (OOT), located at the mouth of the Saguenay River on the north shore of the St. Lawrence River estuary in Quebec, Canada. The trend observed suggest an ongoing decline. Numbers of rusty blackbirds varied considerably between years, with peak movements occurring at 5-y intervals and possibly reflecting high reproductive success for those years. The numbers of adult boreal owls caught and banded at the OOT, and the proportion of juveniles, were negatively and positively correlated with rusty blackbird numbers, respectively. Peaks in rusty blackbird abundance occurred when red-backed voles (Clethrionomys gapperi) were abundant in the eastern boreal forest. Also, rusty blackbird numbers were positively correlated to the annual and winter North Atlantic Oscillation (NAO) indices and negatively to the combined precipitation for June, July, and August, suggesting that environmental factors may have contributed both directly and indirectly (through food web processes) to the cyclic variations in abundance observed. Current declines may be exacerbated by NAO fluctuation patterns, that is, more frequent negative indices may negatively affect reproductive success and possibly winter survival.

Proceedings Of The Ninety-Second Annual Meeting

The Ninety-sixth Annual Meeting of The Wilson Ornithological Society was held in joint conference with the Association of Field Ornithologists and the Society of Canadian Ornithologists-Societe des ornithologistes du Canada, from Wednesday, 15 July, through Sunday, 19 July, 2015, on the campus of Acadia University in Wolfville, Nova Scotia, which hosted the meeting. Dave Shutler of the Department of Biology, Acadia University, chaired the Committee on Local Arrangements, which also included Colleen Barber, Andrew Boyne, Carina Gjerdrum, Andrew Horn, Marty Leonard, Mark Mallory, Cindy Staicer, and Phil Taylor, with help from Terry Aulenbach, Avery Bartel, Brenda Bigelow, Morgan Brown, Duane Currie, Tammy Gregory, Kayoung Heo, Christine Kendrick, Katrien Kingdon, Sarah Klapstein, Sarah MacDougall, Emma McIntyre, Karissa Reischke, Brent Robicheau, Dave Schultz, Larissa Simulik, Richard Stern, Dan Sweeney, Lisa Taul, Allison Walker, Jake Walker, Nicole Weisner, and Brett VanBlarcom. The Council met from 13:08 to 17:14 on Wednesday, 15 July, and again from 08:37 to 12:16 on Thursday, 16 July, in the Acadia Room of the K. C. Irving Environmental Science Centre, Acadia University. That evening (Thursday) there was an icebreaker opening reception for the conferees and guests at Fountain Commons. The scientific program began on Friday morning in Festival Theater with the WOS Margaret Morse Nice Plenary Lecture, cosponsored by SCO-SOC, delivered by the 2015 Margaret Morse Nice Medal recipient, Erica (Ricky) Dunn, Research Scientist Emeritus, Environment Canada, and titled “Bird observatories: diversity and opportunity.” On Saturday morning James F. Dwyer, Research Scientist, EDM International, presented the AFO plenary lecture, “Range sizes and habitats of nonbreeding Crested Caracaras: implications for the evolution of communal roosting.” The scientific program also included 98 papers organized into 12 sessions; 20 papers organized into three symposia on the ecology and conservation of landbird species at risk: Rusty Blackbirds (Euphagus carolinus) and Canada Warblers (Cardellina canadensis), measuring the impact of bird conservation programs, and bird migration in Atlantic Canada and the Gulf of Maine; and 68 poster presentations. On Friday and Saturday morning, before the plenary sessions, the Local Committee hosted field trips to local birding spots, including Miner’s Marsh and Evangeline Beach. On Sunday, conferees enjoyed longer outings, including a trip to Brier Island to observe pelagic birds and whales, a visit to Cape Split on the Bay of Fundy, and a tour of four local wineries. On Saturday evening there was a social gathering prior to the annual banquet. The evening events included dinner and afterwards Acting WOS Secretary Lindsey Walters, on behalf of all assembled, thanked the Local Committee for a successful conference. She then commended retiring WOS President Bob Curry for his many contributions to the society thus far, as the society looks forward to his continued service in his new role as First Past-President. The following WOS awards, grants, and commendations were presented at the banquet:

A Loose Colony of Rusty Blackbirds Nesting in Northern Maine

Abstract Euphagus carolinus (Rusty Blackbird) has suffered a steep population decline over the past 40 years, yet we still understand little of the basic biology of the species, particularly its social organization. During the spring of 2007, we located a loose colony of Rusty Blackbirds breeding in Piscataquis County, ME. The core colony consisted of six nests within 6.9 ha. These nests were located within a 70-ha clearcut dominated by regenerating Picea rubens (Red Spruce), P. mariana (Black Spruce), and Abies balsamea (Balsam Fir). Within 1500 m of the core colony, we located two “satellite” nests in young forests regenerating from heavy partial harvests. We observed mobbing behavior by multiple individuals from different pairs, suggesting that coloniality in this species may be an antipredator strategy.

Implications of Prebasic and a Previously Undescribed Prealternate Molt For Aging Rusty Blackbirds

Abstract. Aging birds often relies on differences in plumage between immatures and adults, and understanding these patterns can improve our ability to discern demographic patterns within populations. We investigated patterns of prebasic molt of the Rusty Blackbird (Euphagus carolinus) in fall at Whitehorse, Yukon Territory, and developed a new technique for aging based on characteristics of the head plumage acquired during prebasic molt. Furthermore, we investigated the possibility of a prealternate molt among wintering Rusty Blackbirds on the basis of captures in Mississippi and museum specimens from across the species' winter range. Finally, we examined how a prealternate molt might affect the aging of winter birds by plumage. Rusty Blackbirds completed their prebasic molt by the end of September, and immature birds had a more prominent eye ring and a paler chin than adults, allowing a reliable age determination. Previously, the Rusty Blackbird was thought to attain its breeding plumage through feather ...

Home Ranges of Rusty Blackbirds breeding in Wetlands: How Much Would Buffers From Timber Harvest Protect Habitat?

We calculated the home ranges and core areas of 13 adult Rusty Blackbirds (Euphagus carolinus) in Maine to determine (1) the area requirements of breeding adults, (2) whether area requirements of the sexes and of colonial and noncolonial individuals differ, and (3) the proportion of the home range and core area that would be protected by a buffer of no logging of 50–100 m around occupied wetlands. Mean home ranges (37.5 ± 12.6 ha) and core areas (11.1 ± 2.8 ha) were large in comparison to those of other breeding icterids, and adults often foraged in multiple unconnected wetlands. Rusty Blackbirds that were part of a loose colony had home ranges and core areas three times larger than those of pairs that nested solitarily, which we speculate may be due to adults following one other to feed on unpredictable emergences of aquatic insects. Home ranges and core areas included a surprisingly small amount of wetland habitat, only 12% and 19% respectively, but adults often foraged in small wet patches (<16 m2) in otherwise upland habitat. The 75-m buffers around wetlands that we recommended in a concurrent study may help protect the Rusty Blackbird's nesting habitat, but such buffers contained less than half the average home range, suggesting that they may be of only limited benefit as a conservation strategy for protecting foraging habitat.

Rusty Blackbird: Mysteries of a Species in Decline

Abstract. The Rusty Blackbird (Euphagus carolinus) breeds across the boreal forest zone of North America and winters throughout the eastern United States. Over the past four decades, the North American Breeding Bird Survey and the Christmas Bird Count have shown high rates of population decline ranging from approximately 5 to 12% per year. Regional surveys suggest declines and range retractions in the southern boreal zone. Analyses of historical accounts suggest that the Rusty Blackbird's abundance has been dropping steadily for over a century. A number of hypotheses have been proposed to explain the decline. The species relies on wooded wetlands throughout the year, so loss and degradation of these habitats—particularly in the winter range—is a prime suspect. Blackbird-control programs may have contributed. In recent decades, habitat disturbance, global warming, and environmental contamination in the boreal zone may have taken their toll on breeding populations. In 2005, the International Rusty Blackbird...

Migratory Connectivity in the Rusty Blackbird: Isotopic Evidence From Feathers of Historical and Contemporary Specimens

Abstract. The Rusty Blackbird (Euphagus carolinus) has declined dramatically across its range in North America since at least the 1960s, but the causes for this decline are unknown. We measured ratios of stable hydrogen isotopes (δD) in feathers collected from Rusty Blackbirds wintering in the Mississippi Alluvial Valley (n = 255 birds) and the coastal plain of South Carolina and Virginia (n = 281 birds), 2005–2009, to estimate the region of origin of birds wintering west and east of the Appalachians, respectively. We also measured δD values in feathers from all available museum specimens collected from 1879 to 1990 in these same two regions (n = 190 birds). Isotopic values support migratory connectivity in this species with breeding populations in the western and central boreal forest migrating through a central or Mississippi flyway and those breeding in the eastern boreal forest migrating to a winter range east of the Appalachians. We detected little long-term change in the breeding origins of modern a...

Habitat Occupancy by Rusty Blackbirds Wintering in the Lower Mississippi Alluvial Valley

The Rusty Blackbird (Euphagus carolinus) has declined by 90% since the 1960s, possibly from conversions of forested wetlands in the southeastern U.S. to agriculture. Because its habitat use during the nonbreeding season had not been quantified, we estimated occupancy rates of Rusty Blackbirds wintering in the lower Mississippi Alluvial Valley in relation to habitat type (four types of bottomland forest and adjacent agricultural fields), tree density, canopy cover, and water cover. In January and February, we surveyed 89 sites eight times during 2006, 117 and 109 sites 10 times during 2007 and 2008, respectively. Occupancy of individual birds, estimated from their presence or absence at a site, was generally high and greater in 2006 (0.71) than during either 2007 (0.43) or 2008 (0.37). Occupancy of flocks, estimated from presence or absence of ≥20 individuals, was highest in 2006 (0.46), lowest in 2007 (0.17), and intermediate in 2008 (0.30), possibly because of water levels fluctuating from year to year. Rusty Blackbirds were not as specialized in habitat use as expected; habitat characteristics did not consistently predict occupancy of either individuals or flocks. Occupancy of individuals increased with canopy cover during 2007, and occupancy of flocks decreased with tree density during 2006. In 2008, occupancy of individuals increased with tree density and was higher in wet bottomland forest (0.51) than in other habitats (0.31–0.35). Further research is needed to determine whether this lack of habitat specificity is widespread and possibly the result of diverse food requirements during the nonbreeding season.

Prevalence of Hematozoa Infections Among Breeding and Wintering Rusty Blackbirds

Abstract. The Rusty Blackbird (Euphagus carolinus) has declined precipitously over the past several decades, and stressors on both the breeding and wintering grounds are suspected causes. Over 3 years, we collected blood samples from breeding birds in Alaska and Maine and from wintering birds in Mississippi and Arkansas to determine the prevalence of hematozoan infections at different times of the year. The prevalence of hematozoa (percent of birds infected) in Alaska was 44% of 43 birds, lower than previously reported from Newfoundland and Ontario (83% of 23 birds). Blood parasites were found among 67% of 12 Rusty Blackbirds sampled in Maine, not different from the prevalence in Newfoundland and Ontario. Leucocytozoon was the most common parasite; few breeding birds were infected with Plasmodium or Trypanosoma sp. During the winter in Mississippi and Arkansas, the overall prevalence of hematozoa was 49% over three years. In winter as in summer, Leucocytozoon was the most commonly encountered parasite (n ...

Estimating the Abundance of Nesting Rusty Blackbirds in Relation to Wetland Habitats in Alaska

Abstract. We used double sampling to estimate densities of Rusty Blackbird (Euphagus carolinus) nests among boreal wetlands in Anchorage and Tanana Flats, Alaska, 2007–2008. We also assessed habitat selection by examining the number and location of nests relative to the availability of various wetland types. We rapidly surveyed 78 sample units for adult Rusty Blackbirds and intensively searched for nests in a subset of 55 units to determine actual numbers of nests. Rapid surveys detected 97% of the 75 nests when we restricted counts to pairs and lone females. They overestimated nest numbers by 17% when we included in the counts lone males, which sometimes made long flights within and between sample units. Nest densities in sampled wetlands averaged 2.2 and 3.4 nests km 2 in Anchorage and Tanana Flats, respectively, surprisingly similar despite wetlands being rare in Anchorage. An abundance of wetlands made identifying important breeding habitats difficult on the Tanana Flats, where blackbirds used most we...

Nest-Site Selection and Nest Survival of the Rusty Blackbird: Does Timber Management Adjacent to Wetlands Create Ecological Traps?

Abstract. Animals are subject to ecological traps when anthropogenic changes create habitat that appears suitable but when selected results in decreased fitness. The Rusty Blackbird (Euphagus carolinus) breeds in boreal wetlands and has declined by 85–95% over the last half century. We studied nest-site selection and daily nest-survival rate (DSR) of 43 Rusty Blackbird nests in northern New England and evaluated whether regenerating logged areas adjacent to wetlands created ecological traps. Although nesting adults avoided high-canopied forests and selected areas with dense balsam fir (Abies balasmea) 1 to 3 m high, those characteristics were not associated with DSR. Conversely, the frequency of speckled alder (Alnus incana) and sedges (Cyperaceae) in the nest plot varied with DSR, suggesting that the risk of predation of nests within wetlands was lower. DSR also varied with past logging; nests in plots not harvested recently were 2.3× more likely to fledge young than nests in plots harvested within 20 ye...

Nesting Ecology of the Rusty Blackbird in Alaska and Canada

Abstract. We examined the nesting ecology of the Rusty Blackbird (Euphagus carolinus) from 162 nests monitored for nest survival in Alaska and 252 incidental records from Alaska and Canada to identify important habitats for nesting and to test whether low rates of nest success are contributing to populations declines in Alaska. In coastal Alaska and throughout Canada, nests were primarily in conifers (85% of 212 nests). All conifer nests in Alaska and 80% of those in Canada were placed in spruce (Picea spp.), primarily black spruce (P. mariana). In Alaska use of small spruces (<8 cm dbh) was selective and resulted in high reproductive success—nest survival increased with black spruce density, and success of nests in spruce (79%) was higher than that of nests in deciduous vegetation (52%). Survival of nests in taller spruce declined, possibly from predation by red squirrels (Tamiasciurus hudsonicus). Rusty Blackbirds nested near water in interior ( = 8 m) and south-central Alaska ( = 30 m), and small spruc...

Geographic and Seasonal Variation in Mercury Exposure of the Declining Rusty Blackbird

Recent evidence suggests that mercury exposure has negative effects on the health of songbirds, and species that forage in wetlands may be at a greater risk of bioaccumulation of mercury than are those of other habitats. We examined mercury concentrations in blood and feathers from the wetland obligate and rapidly declining Rusty Blackbird (Euphagus carolinus) from five regions across North America: three wintering areas in the contiguous United States and breeding areas in the western boreal forests of Alaska and the Acadian forests of northeastern North America. In blood, mercury concentrations in Rusty Blackbirds from the Acadian forest (geometric mean 0.94 µg g-1; n = 59) were >3× than in those from Alaska (0.26 µg g-1; 107). Wintering birds had blood mercury levels approximately an order of magnitude lower than those of breeding birds (0.07 µg g-1; 332). In feathers, mercury concentrations in samples from the Acadian forests exceeded published minimum levels for adverse effects on birds (8.26 µg g-1; 45) and were 3× to 7× those observed from the other regions. The mercury concentrations we report in blood and feathers of the Acadian forest population of the Rusty Blackbird are among the highest reported for wild populations of passerines at sites without a known local source of mercury. Mercury should be considered as a potential contributor to the species' dramatic population decline in New England and the Maritime provinces and in other areas where bioavailability of mercury is high.

Retrospective Comparison of the Occurrence and Abundance of Rusty Blackbird in the Mackenzie Valley, Northwest Territories

Machtans, C. S., S. L. Van Wilgenburg, L. A. Armer, and K. A. Hobson 2007. Retrospective comparison of the occurrence and abundance of Rusty Blackbird in the Mackenzie Valley, Northwest Territories. Avian Conservation and Ecology - Écologie et conservation des oiseaux 2(1): 3.http://dx.doi.org/10.5751/ACE-00106-020103

On the Decline of the Rusty Blackbird and the Use of Ornithological Literature to Document Long‐Term Population Trends

Abstract: Unlike most North American blackbirds, Rusty Blackbirds ( Euphagus carolensis) have shown steep population declines. Declines of approximately 90% are indicated for three recent decades from the Breeding Bird Survey, Christmas Bird Counts, and Quebec Checklist Program. Analyses of abundance classifications in bird distribution books and annotated checklists reveal an overlooked but long‐term decline dating back to at least the early part of this century. Rusty Blackbirds were described as very common to abundant in 56% of the pre‐1920 published accounts, 19% of the 1921–1950 accounts, and only 7% of the post‐1950 accounts. Rusty Blackbirds were described as uncommon in none of the pre‐1950 accounts, 18% of the 1951–1980 accounts, and 43% of the post‐1980 accounts. A similar pattern was found for analyses based on local checklists. Destruction of wooded wetlands on wintering grounds, acid precipitation, and the conversion of boreal forest wetlands could have contributed to these declines. Systematic analysis of regional guides and checklists provides a valuable tool for examining large‐scale and long‐term population changes in birds.

Riparian edge effects on boreal balsam fir bird communities

Riparian forests are often identified as prime habitat for wildlife because of the presence of particular plant communities and edges creating a highly developed and diversified vegetation structure. However, in the northeastern boreal forests of Canada, where narrow land–water ecotones with abrupt edges are quite common, the relative habitat value of riparian forests remains to be demonstrated. We compared bird communities of eight pairs of riparian and nonriparian plots, similar in vegetation structure and composition, to verify the relative value for breeding birds of typical coniferous riparian forest stands of the southern boreal region of eastern Quebec. Bird abundance (P = 0.02), richness (P = 0.03), and diversity (P = 0.02) were significantly higher in the riparian stands, where the spatial sequence of three distinct habitats (a balsam fir (Abiesbalsamea (L.) Mill.)–northern white cedar (Thujaoccidentalis L.) forest, a narrow alder (Alnusrugosa (Du Roi) Spreng.) - grass wetland, and water) created high horizontal vegetation diversity. In riparian stands median bird richness and density were, respectively, 23.5 species and 437.5 territories/km2 compared with 19.0 species and 348.2 territories/km2 for interior stands. Nine species were observed exclusively in riparian plots. In addition to the species usually found in the studied nonriparian forests, the riparian plots were used by species typically related to the water edge such as the Northern Waterthrush (Seiurusnoveboracensis Gmelin) and Rusty Blackbird (Euphaguscarolinus Miiller) as well as species associated with the shrub and grass wetland such as the American Robin (Turdusmigratorius L.), the Veery (Catharusfuscescens Stephens), and the Common Yellowthroat (Geothlypistrichas L.). The shrub-foraging guild showed higher abundance in riparian stands. The tree-foraging and tree-bole foraging guilds, however, were comparable in both groups of stands. In this study, the natural conditions prevailing along he riparian sites appeared mostly positive for the breeding-bird community; it created what is perceived as being an "edge effect." The edge effect can be defined, in this case, as being the additional density and number of species induced by the added horizontal vegetation diversity created by the close association of three extremely different ecosystems: a forest stand, an aquatic ecosystem, and a narrow but distinct shrub-grass wetland. This also confirms the necessity of distinguishing natural edges that are permanent features of the landscape from induced edges created by human activity.

Solitary Sandpiper Early Reproductive Behavior

THE Solitary Sandpiper (Tringa solitaria) is among the least known of Nearctic birds, primarily because of its inaccessibility during the breeding season. The species nests about muskeg and woodland pools using old nests of such passeriform species as the Rusty Blackbird (Euphagus carolinus), Robin (Turdus migratorius), Common Grackle (Quiscalus quiscula), Cedar Waxwing (Bombycilla cedrorum), Bohemian Waxwing (B. garrulus), Eastern Kingbird (Tyrannus tyrannus), and Gray Jay (Perisoreus canadensis). It is not known if they ever preempt nests, but at least occasionally they use freshly made nests (D. F. Parmelee, pers. comm.). Eggs have been found from 1.2-12 m above the ground and from the shoreline to 200 m away, usually in conifers but sometimes in deciduous trees (Henderson 1923, Street 1923, Bent, 1929, Sutton in Bannerman 1958) and rarely (perhaps) in cattail (Todd 1963). T. solitaria is also known to be solitary and, perhaps, territorial year-round; and does not migrate in flocks as do most waders (Hudson 1920, Todd and Carriker 1922, Wetmore 1926, Sutton in Bannerman 1958). This unique combination of solitary and arboreal habits makes solitaria of special interest, and the paucity of information concerning Solitary Sandpiper behavior leads me to present my data despite their preliminary nature. I published data on acoustical behavior separately (Oring, 1968).

The Nasal Mites of Birds from Louisiana. IV. The Genus Ptilonyssus (Dermanyssidae: Rhinonyssinae) with a Description of Two New Species

A new species and new host records are established for nasal mites of the genus Ptilonyssus from passeriform birds in Louisiana. Ptilonyssus corvi sp. n. is described from Corvus brachyrhynchos. New host records are Ptilonyssus tyrannus from Sayornis phoebe, Contopus virens, and Epidonax virescens, P. callinectoides from Myiarchus crinitus, P. pari from Parus carolinensis, P. hoseini from Vireo solitarius, P. pirangae from Parus bicolor, P. icteridius from Icterus galbula and Euphagus carolinus, P. morofskyi from Geothlypis trichas, Dendroica coronata, D. pinus, Seiurus motacilla, Melospiza georgiana, Pipilo erythrophthalmus, Ammospiza maritima, and Zonotrichia albicollis. In addition, P. vireonis and P. angrensis from Vireo olivaceus and Progne subis, respectively, are reported for the first time from Louisiana. The systematics and host relationships of these species are discussed. Studies on the nasal mites of Louisiana birds have revealed a new species, new host records, and new geographic records for the rhinonyssine genus Ptilonyssus. The present study is concerned with Ptilonyssus sensu lato, or those species which have two dorsal plates, the podosomal and opisthosomal, and chelicerae of uniform diameter or only slightly attenuated at the distal end. The materials and methods, including the designations and abbreviations used in the following descriptions, have been outlined previously (Pence, 1972). Genus Ptilonyssus Berlese and Trouessart Ptilonyssus Berlese and Trouessart, 1889, Bull. Biblioth. Sci. Ouest 2: 128. Synonymy (see Domrow, 1969, Proc. Linn. Soc. N.S.W. 93: 333).

The Nasal Mites of Birds from Louisiana. III. The Genus Ptilonyssus (Dermanyssidae: Rhinonyssinae) with Description of a New Species

A new species and new host records are established for nasal mites of the genus Ptilonyssus from passeriform birds in Louisiana. Ptilonyssus corvi sp. n. is described from Corvus brachyrhynchos. New host records are Ptilonyssus tyrannus from Sayornis phoebe, Contopus virens, and Epidonax virescens, P. callinectoides from Myiarchus crinitus, P. pari from Parus carolinensis, P. hoseini from Vireo solitarius, P. pirangae from Parus bicolor, P. icteridius from Icterus galbula and Euphagus carolinus, P. morofskyi from Geothlypis trichas, Dendroica coronata, D. pinus, Seiurus motacilla, Melospiza georgiana, Pipilo erythrophthalmus, Ammospiza maritima, and Zonotrichia albicollis. In addition, P. vireonis and P. angrensis from Vireo olivaceus and Progne subis, respectively, are reported for the first time from Louisiana. The systematics and host relationships of these species are discussed. Studies on the nasal mites of Louisiana birds have revealed a new species, new host records, and new geographic records for the rhinonyssine genus Ptilonyssus. The present study is concerned with Ptilonyssus sensu lato, or those species which have two dorsal plates, the podosomal and opisthosomal, and chelicerae of uniform diameter or only slightly attenuated at the distal end. The materials and methods, including the designations and abbreviations used in the following descriptions, have been outlined previously (Pence, 1972). Genus Ptilonyssus Berlese and Trouessart Ptilonyssus Berlese and Trouessart, 1889, Bull. Biblioth. Sci. Ouest 2: 128. Synonymy (see Domrow, 1969, Proc. Linn. Soc. N.S.W. 93: 333).