Bee Fauna of Deer Flat National Wildlife Refuge Canyon County, Idaho Prepared by: Joseph Engler, Wildlife Biologist (retired), U.S. Fish and Wildlife Service, Portland, Oregon Erin Stockenberg, Region 1 Inventory & Monitoring Data Manager, U.S. Fish and Wildlife Service, Portland, Oregon Jason Romine, Fish and Wildlife Biologist, U.S. Fish and Wildlife Service, Burbank, Washington Annette de Knijf, Refuge Manager, U.S. Fish and Wildlife Service, Nampa, Idaho Disclaimer: ‘‘The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service.’’ 1 16 February 2018 Introduction The Pacific Region (Region 1) of the U.S. Fish and Wildlife Service (Service) initiated a bee inventory program to document the bee fauna at National Wildlife Refuges (NWR) in Washington, Oregon, and Idaho from 2010-2016. Sixteen NWRs and one Bureau of Land Management site was sampled during this time frame. Refuges inventoried include: Deer Flat NWR, Minidoka NWR, Kootenai NWR in Idaho; Little Pend Oreille NWR, Turnbull NWR, Hanford National Monument, McNary NWR, Conboy Lake NWR, Pierce NWR, Steigerwald Lake NWR, Ridgefield NWR, Julia Butler Hansen Refuge for Columbia White-tailed Deer, Lewis and Clark NWR, Willapa NWR, and Protection Island NWR in Washington; and Malheur NWR in Oregon. Appendix 1 and 2 show the location of each NWR and the corresponding Bailey’s Province and Ecoregion Section inventoried from 2010-2016. In addition, the Bureau of Land Management’s Oregon Trail Interpretive Center was included as part of this inventory effort. Deer Flat NWR (herein referred to as the Refuge) was sampled during the 2011 and 2012 seasons. This refuge-specific report is one of a series that provides the results of this bee inventory effort in the Pacific Northwest. Study Site The Refuge is located in Canyon County, west of the City of Nampa, Idaho (Map 1 and Title Page) and within the Snake River Basin. The Refuge is situated within the Intermountain Semi-Desert Province (Bailey 1995). Inventory transects are further characterized in this report as Mixed Evergreen-Deciduous Shrubland (Visitor Center transect) and Deciduous Open Tree Canopy (Shop Transect) within the Landfire subclass schema (Landfire 2008). Map 2 shows the habitat classification for the refuge and surrounding area. The refuge is characterized by the 10,528-acre man-made Lake Lowell which stores water for agricultural use. Water is diverted from the Boise River through the 40-mile New York Canal to fill the lake. The “native” habitat surrounding the lake is shrub-steppe dominated by sagebrush (Artemisia spp) including bitterbrush (Purshia tridentate), fourwing saltbush (Atriplex canescens), gray/green rabbitbrush (Chrysothamnus spp.), greasewood (Sarcobatus vermiculatus), spiny horsebrush (Tetradymia spinosa), and spiny hopsage (Grayia spinosa). The understory consists of native bunch grasses and forbs including bluebunch wheatgrass (Pseudoroegneria spicata), Indian ricegrass (Achnatherum hymenoides), squirreltail bottlebrush (Elymus elymoides), steppe bluebunch, Idaho fescue (Festuca idahoensis), Great Basin wildrye (Leymus cinereus), and Sandberg’s bluegrass (Poa secunda). However, due to the long history of ranching, farming and residential development in the area, noxious and invasive species have supplanted the native species. These invasive plants include cheatgrass (Bromus tectorum), Canada (Cirsium arvense) and Scotch thistles (Onopordum acanthium), rush skeletonweed (Chondrilla juncea), perennial pepperweed (Lepidium latifolium), purple loosestrife (Lythrum salicaria), puncturevine (Tribulus terrestris), tamarisk (Tamarix spp.), and Russian olive (Elaeagnus angustifolia). 2 16 February 2018 Map 1. Location of Deer Flat NWR and Bee Inventory Transects Most of the surrounding private lands consist of high intensity farming with little natural lands interspersed for 10-30 miles in all directions, thus impeding dispersal of some wildlife including bees. An artificial corridor was created with the construction of the irrigation infrastructure associated with the New York Canal, the Lake Lowell Reservoir, and its inflows and outflows. It is likely that certain wildlife species, including pollinators, would travel along this corridor. Major crops include alfalfa, pasture/hay, corn, pasture/grass, winter wheat, dry beans, herbs, sugar beets, onions, and potatoes. The Soil Survey of Canyon Area, Idaho (Priest et al. 1972) describes the soils surrounding Lake Lowell as primarily consisting of a mix of Vickery and Marsing soils with lesser areas of Scism, Purdam, Power-Purdam, and Bram soils. Some of the areas on the Refuge lands immediately surrounding Lake Lowell are mapped as Marsh and the lake itself, of course, is mapped as Water. With the exception of the Bram soils, which are somewhat poorly drained, the soils mapped on the Lake Lowell Unit are well drained. Riparian habitat was created with the completion of the New York Canal flowing into the Refuge. Over time, lush vegetation and trees established creating a relatively thin ribbon of riparian forest around Lake Lowell, and especially in the southeast corner of the Refuge where the canal enters the lake. The riparian forests on the Refuge are dominated by invasive and non- native plants with little representation of species native to riparian habitats in the region (e.g., willows). Upper canopy is characterized by cottonwood with an understory dominated by Russian 3 16 February 2018 olive, false indigo bush, and some tamarisk, with a small native component of willows (e.g., coyote willow (Salix exigua), peachleaf willow (Salix amygdaloides)], wild rose (Rosa acicularis), golden currant (Ribes aureum), elderberry (Sambucus spp.), and skunkbush sumac (Rhus trilobata). The herbaceous layer is dominated by invasive species such as reed canarygrass (Phalaris arundinacea), Canada thistle, perennial pepperweed, and purple loosestrife. In the past, the Refuge has used a cooperative farmer to farm between 100 and 300 acres, leaving about 25% of the crop in the ground to provide food for wildlife as the Refuge’s share. Alfalfa, winter wheat, barley, corn, and dry beans have been grown. Farming has not occurred on the Refuge since 2016, as the cooperative farmer did not feel he could make a profit while adhering to new guidelines regarding GMOs, herbicides, and neonicotinoids. Management is currently examining how best to use those farm fields in the future. This portion of Idaho has an arid climate with winter temperatures averaging 30° and summer temperatures averaging 75°; temperatures range from a record high of 109° to a record low of minus 26°. Precipitation falls mainly as snow with annual precipitation averaging 11 inches. Transects were located near the visitor center and maintenance shop and are designated as 18 and 19 on Map 1 and Map 2. The visitor center transect is located just off the Observation Hill Trail system approximately 154 yards from the visitor center. Habitat at this location is shrub-steppe dominated by cheatgrass understory. Visitors enjoy hiking this trail, but exact numbers for how many people use this trail is not available. The shop transect is located immediately northwest of the maintenance shop in a lawn area that receives regular watering and mowing. Although clover and other weedy species grow in the lawn, it provides resources for pollinators. Cottonwoods (Populus spp.), black walnut (Juglans nigra), and pines (Pinus spp.) were planted to provide shade. Although the maintenance shop is located in an area closed to the public, staff and volunteer activity occur here. The shop transect is approximately 90 yards from the lake’s edge; whereas, the visitor center transect is approximately 170 yards from the lake’s edge. Methods Baseline sampling was conducted at the Refuge using two-bee bowl (or pan trap) transects. Transects were set near Refuge headquarters/visitor center and the maintenance shop (Map 1 and Table 1) to facilitate sample collection. The sampling protocol uses a thirty-bowl (3.25 ounce Solo cup) transect which is deployed early in the season and run periodically through the autumn. This protocol was recommended by Sam Droege (US Geological Survey) and is further described in the U.S. Fish and Wildlife Service’s National Protocol Framework for the Inventory and Monitoring of Bees (Droege et al. 2016). The primary bee activity season in the Pacific Northwest occurs from early April through October; however, some bee activity may occur almost year-round, especially west of the Cascade Mountains. Based on expert opinion, some bee species may complete their adult free- flying phase in three weeks or less, and thus traps were deployed approximately every two weeks during this time frame to maximize the number of species encountered. Exact start and end dates were dependent on available staffing. 4 16 February 2018 Table 1: Transect Locations for Deer Flat NWR Transect Name Map # Latitude (dd) Longitude (dd) Elevation (ft) MSL Office 18 43.5620 -116.6680 2,581 Shop 19 43.5528 -116.6414 2,555 Map 2: Habitat Classification Map, Deer Flat NWR At the Refuge, the thirty-bowl scheme was divided into two fifteen-bowl transects to attain better coverage of available habitats. Each transect consisted of fifteen bee bowls which were painted in three colors – fluorescent blue, fluorescent yellow, and white. Bowls were placed in roughly a straight line with five meters between bowls, each bowl alternating in color. Bowls are filled about ¾ full with soapy water to capture bees. Each transect was deployed during daylight hours on a single target day or remained out overnight for approximately 24 hours, contents were then collected and the bowls removed from the site. Transects were run approximately every two weeks at the same locations but some variability existed between sites and trapping episodes. 5 16 February 2018 For transects, trap-hours were calculated for each sample on a daily basis when deployed. A sample consisted of all functional bowls (15 or fewer) in a transect. Trap-hours were defined as the total number of hours the transect was operating (capable of catching bees).