(Castor Canadensis) Is Recolonizing the Llano Estacado
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The North American Beaver (Castor canadensis) is Recolonizing the Llano Estacado Garret D. Langlois,,1, Robert D. Cox,1, Philip S. Gipson,1, and Richard D. Stevens,1,2 1Department of Natural Resources Management and 2Natural Science Research Laboratory of the Museum of Texas Tech University, Lubbock, TX 79409 U. S. A. Abstract Five millennia ago, the North American Beaver (Castor canadensis) was extirpated from the Southern High Plains by droughts. Beaver were found to be largely absent from the Llano Estacado, despite exhaustive search efforts. Here we report the first definitive evidence of an extant C. canadensis population recolonizing the Llano Estacado. Resumen Hace cinco milenios, el castor norteamericano (Castor canadensis) fue extirpado de las Altas Llanuras del Sur por las sequías. Se encontró que los castores estaban en gran parte ausentes del Llano Estacado, a pesar de los exhaustivos esfuerzos de búsqueda. Aquí reportamos la primera evidencia definitiva de una población existente de C. canadensis recolonizando el Llano Estacado. Keywords: Brazos River, ecosystem engineer, keystone species, Lubbock, Panhandle Plains, pioneering population, range expansion, urban ecology, West Texas, wetland restoration Correspondence: [email protected] G.D.L.: orcid.org/0000-0001-8498-0891 R.D.C.: orcid.org/0000-0002-4005-1019 P.S.G.: orcid.org/0000-0003-2026-5180 R.D.S.: orcid.org/0000-0002-9821-0633 1 of 10 The North American Beaver (Order: Rodentia, Family: Castoridae, Castor canadensis Kuhl, 1820) is the largest extant rodent native to North America (Hazard 1982). Beaver are semiaquatic, and their habitation along streams is generally conspicuous: family groups will construct burrows, canals, dams, and lodges (Berry 1923; Jackson 1961). Beaver dams are iconic for creating vital wetland habitat by impounding water. For that reason, beaver are a keystone species that engineer ecosystems, affecting natural communities disproportionately greater than would be expected, relative to their local abundance (Rosell et al. 2005; Brazier et al. 2021; Wohl 2021). The fossil record revealed that C. canadensis (hereafter beaver) occurred in north-central Texas less than 125,000 BP (Dalquest 1962). Further evidence of range expansion by southwestern beaver include fossil remains at the New Mexico – Mexico border (Harris 1993), and northwest Arizona (Jass 2002). Beaver colonization of semiarid and arid landscapes (e.g., the American southwest) was almost certainly achieved through a vast network of beaver-dammed streams (Wohl 2021). Following two extensive droughts 6,500 ‒ 4,500 BP (Holliday 1985), beaver were extirpated from the Southern High Plains (Bolen and Flores 1986; Bolen et al. 1989). No evidence of recolonization from neighboring escarpments, nor of an extant beaver population, was reported in 1831‒1832 (Pike 1969), 1986 (Bolen and Flores 1986), 1989 (Bolen et al. 1989), 1994 (Haukos and Smith 1994), or 2003 (Baker and Hill 2003). Further into the 21st century, beaver were still considered to be absent from the Llano Estacado, save Randall County in northwestern Texas (Schmidly and Bradley 2016; Ueda 2020). On the 4th of November 2015, the carcass of an adult beaver (accession number of skull: TTU-M 128469) was found on the bank of Canyon Lake 5 in Mackenzie Park (33°35'24.3"N 101°49'49.9"W), Lubbock, Texas (Garcia et al. 2016). The Canyon Lakes are a series of six narrowly constructed lakes, considered relatively drought proof (HDR Engineering, Inc. 2018), because a substantial portion of their inflow is reclaimed municipal effluent (Winn 1973). This lake system follows the North Fork of the Double Mountain Fork of the Brazos River, an intermittent stream which runs through Yellow House Canyon (Winn 1973). The occurrence of that specimen in Canyon Lake 5 was considerably disjunct from the known range of beaver in the Panhandle Plains (Garcia et al. 2016; Schmidly and Bradley 2016). Garcia et al. (2016) speculated that the specimen had not been anthropogenically translocated, but arrived alive and 2 of 10 under its own power, likely during the high waters of summer 2015 via eastern ingress. No further evidence of beaver was presented beyond that single carcass. Southeast from Canyon Lake 5 is Canyon Lake 6, and the parks of Mae Simmons and Dunbar Historical Lake, in that order. Mae Simmons is a 98.3 acre semi-natural recreational park, and one of the more wooded sites along the Canyon Lakes system. We classified the semi- natural portions of the park into four ecological map units of the High Plains ecoregion (Elliott et al. 2014). The southwestern lakeshore was riparian hardwood forest, which contained eastern cottonwood (Populus deltoides) and black willow (Salix nigra) tree species. Southwest of the riparian hardwood forest was a depressional marsh, a natural community distinct from the closed wetland system of a playa. Floodplain hardwood forest grew surrounding the depressional marsh and adjacent to the riparian hardwood forest. Further upland was shortgrass prairie. Considering these habitat types and the natural history of beavers, we hypothesized that if beaver could occur in the Canyon Lakes, they would do so in Mae Simmons Park. In January 2018, we discovered chewed stumps from one to three seasons past, along the shoreline of Canyon Lake 6 in Mae Simmons Park (33°34'39.7"N 101°49'34.1"W). A pattern of fresh evidence appeared the following weeks, and into spring (Figure 1). Encouraged by signs of potential beaver habitation, we conducted water quality analyses, to confirm the suitability of the lakewater for beaver (Table 1). On the 30th of March 2018, we deployed three motion-activated trail cameras (Bushnell Trophy Camera Brown Model 119537; Bushnell Corp., Overland Park, Kansas, U. S. A.). We captured images and video until the 30th of July 2018. With permission from the Lubbock Parks & Recreation Department, trail cameras were placed in discreet, off-trail locations, and programmed to only activate at night. Using these cameras, we documented a pair of beavers on the 8th of July 2018 (Figure 2, Supplementary Material: Video S1). The return of beaver to the Llano Estacado after a multi-millennia absence is significant. This colonization also ushers in the type of human–wildlife challenges that can arise when the public are unaccustomed to a novel animal on the landscape. The public and these beaver have already begun to interact, and some of the beaver have unfortunately become victims of road mortality (Ueda 2019). Monitoring this new population would be advisable to best mitigate potential human–beaver conflicts. This effort could be achieved taxpayer free, as we anticipate broad and enduring community-based enthusiasm for such a project. Long-term monitoring of 3 of 10 these beaver could be conducted by volunteers, and engage municipal educators, and local naturalists both young and old alike. Ultimately, we assert there are more benefits than drawbacks in the recolonization of the Llano Estacado by beaver. These beaver will enhance habitat for semiaquatic furbearers and other mammals, waterfowl and other birds, amphibians, reptiles, fish, and pollinating insects. Especially considering that Lubbock will expand the Canyon Lakes system with the addition of Canyon Lake 7: a 774-acre lake, slated to cost $251 million, and to be completed by the year 2040 (HDR Engineering, Inc. 2018; Texas Water Development Board 2020). Expansions of the Canyon Lakes will very likely be colonized by this pioneering population of beaver. This is a conservation opportunity of mutual benefit for both beaver and the residents of of the Southern High Plains. On rangeland where they have been restored, beaver dams can lengthen seasonal streamflows, raise groundwater levels, reduce streambank incision and erosion, control flooding, improve surface water flows, enhance resilience to drought and wildfire, increase biodiversity, improve aquatic and riparian habitat, and hasten groundwater and well-water recharge rates (Charnley 2018, 2019; Kantor and Charnley 2020; Wohl 2021). If granted the opportunity, beavers could fulfill their role as low-cost ecosystem restoration engineers of the Llano Estacado, which we suggest is worth consideration. Acknowledgments We are grateful for the interdisciplinary collaboration with artists, David Chapman Lindsay and Stephanie Rae Berrie. We appreciate the field support and expertise of Matthew R. Jackson and Robert C. Lee. We are thankful for the laboratory supplies and technical support, provided by Drs. Mark C. Wallace and Matthew A. Barnes. We thank Dr. Lionel Plummer, and the Lubbock Parks & Recreation Department for facilitating site use for this project. The iNaturalist entries of Barry Keith were helpful in spotlighting beaver interactions with the West Texas public. Lastly, we enjoyed interacting with the many friendly and helpful citizens of Lubbock, who approached us while in the field with good-natured curiosity. 4 of 10 References Baker, B. W., and E. P. Hill. 2003. Beaver (Castor canadensis). 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