Moths of the Malheur National Wildlife Refuge
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MOTHS OF UMATILLA NATIONAL WILDLIFE REFUGE: Results from 15 sites sampled July 11-13, 2018 Dana Ross Corvallis, Oregon [email protected] The findings and conclusions in this report are those of the author and do not necessarily represent the views of the U.S. Fish and Wildlife Service. SUMMARY Macro-moths were sampled from the Umatilla National Wildlife Refuge for a fourth time July 11-13, 2018 as part of an ongoing pollinator inventory. Blacklight traps were deployed for a single night at fifteen sites representative of major plant communities within the McCormack and Paterson Units. A total of 335 specimens and 49 macro-moth species – plus an additional 16 micro-moth species – were obtained and are reported here. Of that total, 26 species (40%) were documented from the refuge for the first time. On a somewhat larger geographical scale, 21 species were recorded for the first (4), second (10) or third (7) time from Morrow County, Oregon and 7 species were documented for the first (5) or third (2) time from Benton County, Washington. INTRODUCTION National Wildlife Refuges protect important habitats for many plant and animal species. Refuge inventories have frequently included plants, birds and mammals, yet insects - arguably the most abundant and species- rich group in any terrestrial habitat - have largely been ignored. Small size, high species richness and a lack of identification resources have all likely contributed to their being overlooked. Certain groups such as moths, however, can be easily and inexpensively sampled using light traps and can be identified by regional moth taxonomists. Once identified, many moths can be tied to known larval hostplant species at a given site, placing both insect and plant within a larger ecological context. Moths along with butterflies belong to the insect Order Lepidoptera. The larvae (caterpillars) are consumers of enormous quantities of plant biomass and help to recycle plant nutrients back into the soil. Most adult moths feed on nocturnally available flower nectar and in doing so pollinate many flowering plant species. As egg, larva, pupa or adult, moths are an abundant and essential food resource for myriad species of birds (especially nestlings), bats, rodents, reptiles, amphibians and other insects. Moths are, therefore, an essential component of a healthy and productive ecosystem. Sampling that includes the physical collection of voucher specimens is a critical component of any meaningful insect inventory. Vouchers added to regional repositories serve as indisputable evidence of a study’s findings and contribute to a greater understanding of wing pattern and morphological variability, and, can provide DNA for genetic studies. When moth information (species, date, location, etc.) is compiled within a centralized database (see pnwmoths.biol.wwu.edu) it can lead to a more resolute understanding of each species range, distribution, flight period and relative abundance, and can help to identify rare species and their habitats where conservation may be of interest. Each refuge has a unique assemblage of insects where each species serves one or more specific ecological roles. Moths are a particularly species-rich group of insects yet they remain largely unknown for most important wildlife areas including our national wildlife refuges. The survey results presented here complement the ongoing Umatilla NWR moth inventory initiated in 2015. 1 METHODS A total of fifteen sample sites (Figures 1 & 2, Tables 1 & 2) were selected to capture macro-moth diversity across a variety of major habitat types within the combined McCormack (Morrow County, Oregon) and Paterson (Benton County, Washington) units of the Umatilla NWR (Photos 1-7). Sites included riparian forest, wetland and steppe communities across an eight mile span on both sides of the Columbia River. For consistency, most sites sampled where those that had been used previously. In some instances, a new site was selected when access to an established site had become difficult, if site quality appeared poor, or, if the surveyor deemed it might otherwise benefit the study. Invariably, final trap locations were determined once they were observed first-hand prior to sampling. When possible, traps were placed in locations not visible to the public from primary access roads. The sample period was chosen to coincide with the new moon, a time when interference from ambient moon light is minimal and the attractiveness of light traps is, therefore, optimal. While warm, calm nights with cloud cover are preferable to cold, rainy or windy nights, most moth species are capable of flying during adverse conditions, thus weather was considered of secondary importance to moon phase. For each site sampled, a 12 volt battery-powered light trap unit was run continuously over one full night (from dusk until dawn) with a 22 watt circular UV-blacklight bulb as a visual attractant. Moths hitting the clear acrylic vanes mounted above the trap tumble down through a funnel and into a collection bucket charged with a fumigant (“No Pest Strip”) to quickly kill them. Light traps and associated batteries were retrieved the following morning. Moth samples were placed in plastic baggies and labeled with location and date using a permanent marker pen. Samples were transferred to a refuge freezer until all sampling was complete, then transported via ice chest to Corvallis and again frozen until processed. Processing entailed thawing moths on a large white sheet of paper and sorting/counting all macro-moths and certain recognizable micro-moths to species. Identifications of most moths were straightforward and could be accomplished immediately. Less familiar moths were identified using the Oregon State Arthropod Collection (OSAC, Dept. of Zoology, Oregon State University, Corvallis) and internet-based resources such as the PNW Moths (pnwmoths.biol.wwu.edu) and Moth Photographers Group (mothphotographersgroup.msstate.edu) websites. The most difficult identifications required assistance from other moth experts. One or more voucher specimens for each moth species sampled were retained, mounted and labeled. Each first voucher specimen was deposited in the OSAC collection. Duplicate specimens are available for refuge collections or displays. 2 Figure 1. Map of 2018 Umatilla NWR (McCormack Unit) moth trap locations. 3 Figure 2. Map of 2018 Umatilla NWR (Paterson Unit) moth trap locations. 4 Table 1. Umatilla NWR 2018 moth site GIS attributes I. Trap Code Habitat Date Sampled 2018-1 shrub steppe 7/11/2018 2018-2 shrub steppe/riparian forest edge 7/11/2018 2018-3 shrub steppe/near corn circle 7/11/2018 2018-4 tree/shrub/forb mix 7/11/2018 2018-5 edge of seasonal wetland 7/11/2018 2018-6 shrub steppe 7/12/2018 2018-7 shrub steppe/riparian forest edge 7/12/2018 2018-8 shrub steppe/bitterbrush 7/12/2018 2018-9 seasonal wetland/willow 7/12/2018 2018-10 riparian forest/cottonwood 7/12/2018 2018-11 shrub steppe 7/13/2018 2018-12 steppe/wetland edge 7/13/2018 2018-13 riparian forest/cottonwood-willow 7/13/2018 2018-14 steppe, near river shoreline 7/13/2018 2018-15 steppe/bitterbrush 7/13/2018 Table 2. Umatilla NWR 2018 moth site GIS attributes II. Trap Code Refuge Unit UTM 11T (Easting / Northing) Elevation 2018-1 McCormack 299376 / 5088016 280 feet 2018-2 McCormack 299677 / 5088242 280 feet 2018-3 McCormack 299957 / 5087515 285 feet 2018-4 McCormack 299804 / 5086181 275 feet 2018-5 McCormack 299573 / 5085982 265 feet 2018-6 Paterson 306887 / 5087431 280 feet 2018-7 Paterson 305428 / 5087385 270 feet 2018-8 Paterson 305693 / 5088131 295 feet 2018-9 Paterson 304371 / 5087639 270 feet 2018-10 Paterson 304221 / 5087691 270 feet 2018-11 McCormack 299412 / 5085714 275 feet 2018-12 McCormack 299669 / 5084885 270 feet 2018-13 McCormack 297070 / 5084108 270 feet 2018-14 McCormack 296444 / 5083624 285 feet 2018-15 McCormack 295262 / 5083024 280 feet 5 Photo 1. Shrub-steppe and riparian forest habitats (vicinity Sites 2018-1 & 2, McCormack Unit). 6 Photo 2 (Cover Photo). Blacklight trap in shrub steppe near corn circle habitat (Site 2018-3, McCormack Unit). 7 Photo 3. Blacklight trap in steppe/wetland edge habitat (Site 2018-12, McCormack Unit). 8 Photo 4. Blacklight trap in riparian forest habitat (Site 2018-13, McCormack Unit). 9 Photo 5. Blacklight trap in shrub steppe habitat (Site 2018-6, Paterson Unit). 10 Photo 6. Blacklight trap in shrub steppe/bitterbrush habitat (Site 2018-8, Paterson Unit). 11 Photo 7. Blacklight trap in seasonally wet willow habitat (Site 2018-9, Paterson Unit). 12 RESULTS & DISCUSSION A total of 335 individual macro-moths representing 49 species, plus an additional 16 species of micro-moths, were sampled from 15 moth traps combined (Table 4). Of those, 40% (26 species) were sampled from the refuge for the first time. On average, each sample included just 22 individuals and 8 species of macro-moths. Samples ranged in size from 4 to 72 moths and included from 3 to 15 species (Table 3). The greatest moth abundance and number of species came from Site 2018-10 in the Paterson Unit within the understory of a riparian/cottonwood forest. Of the 15 species sampled there, Digrammia decorata (Geometridae) accounted for 38 of the 72 specimens. Within the McCormack Unit, samples from Site 2018-2 (shrub steppe/riparian forest interface) and Site 2018-12 (riparian forest with cottonwood and willow) each contributed 14 species. Three sites contributed extremely few moths to the total. In the Paterson Unit, Site 2018-8 (steppe/bitterbrush) produced just 4 individuals and 3 moth species. Similarly, Site 2018-3 (shrub steppe near corn circle) and Site 2018-5 (edge of seasonal wetland) in the McCormack Unit each captured only 4 individuals representing 4 species. Extremely dry conditions likely contributed to the low moth abundance, although insecticide drift from the surrounding agricultural fields cannot also be ruled out.