Capturing pests and releasing ecosystem engineers: translocation of common but diminished species to re‐establish ecological roles

Abstract

Translocation of abundant but declining ecologically important species for re‐establishing more sustainable ecosystem function is a neglected but promising form of conservation intervention. Here, we developed a translocation program in which we capture pests and release ecosystem engineers, by relocating California ground squirrels Otospermophilus beecheyi from areas where they are unwanted to conserved lands where they can perform ecosystem services such as burrowing and vegetation alteration. We accomplished this using an experimental approach in which some factors were measured or experimentally manipulated, while others were held constant. We translocated 707 squirrels and examined survival and movement patterns as a function of several translocation tactics and ecological factors. We released squirrels at 9 different plots with varying ecological contexts and at each plot experimentally manipulated post‐release habitat using mowing, mowing plus the use of augers to establish starter burrows, and controls that remained unmanipulated. The most influential variables affecting short‐term survival, dispersal, and long‐term persistence were factors relating to soils and vegetation structure. Translocated squirrels had higher initial survival on plots where dense exotic grasses were experimentally altered, greater dispersal when released at sites with less friable clay soils, and improved long‐term persistence at sites characterized by more friable soils associated with metavolcanic than alluvial geological layers. Squirrel persistence was also improved when translocations supplemented previous translocation sites than during initial translocations to sites containing no resident squirrels. Our results demonstrate how California ground squirrels can be successfully translocated as part of a larger objective to favorably alter ecological function in novel grassland ecosystems dominated by non‐native vegetation. In broader context, our study highlights the importance of testing release strategies, and examining habitat variables and restoration techniques more closely when selecting release sites to improve translocation outcomes.

Conditioned odor aversion as a tool for reducing post‐release predation during animal translocations

“…Rabbit translocations are not, therefore, recommended in consecutive years in the same areas (Cabezas & Moreno, 2007; Ruiz‐Aizpurua & Tortosa, 2018). This procedure has, however, been recommended for other similar ecosystem engineer species such as ground squirrels (Swaisgood et al ., 2019). Secondly, the study area suffered from a severe drought during the fall of 2017, with a water deficit of 51.2 mm, in contrast to the excess of water of 79.4 mm in 2016 (SIAR, 2019).…”

“…In those cases in which predation has been effectively reduced, it has been through the systematic use of poison and trapping over time and on a wide spatial scale (Short et al ., 1992; Armstrong et al ., 2006). The creation of fences for the exclusion of predators, and the use of poison or lethal control on a large scale and in a systematic manner, have high economic and ecological costs which prevent their extensive use (Short et al ., 1992; Rouco et al ., 2008; Lennox et al ., 2018), signifying the need to explore other approaches (Moseby et al ., 2015; Swaisgood et al ., 2019).…”

“…With regard to the maintenance of ecological systems, a sufficient number of individuals is required, not only to prevent species extinction, but also to perform ecological roles (Gaston, 2010). This is the case of those keystone species that function as key prey or ecosystem engineers (Delibes‐Mateos et al ., 2007; Swaisgood et al ., 2019), which may be pests in some regions and ecologically important species as regards re‐establishing ecosystem functions in others (Delibes‐Mateos et al ., 2008 a ; Swaisgood et al ., 2019). One example of these species is the European rabbit Oryctolagus cuniculus , thousands of which have been translocated onto hunting estates and into conservation areas in order to reinforce the populations of this key species as a prey for several endangered species, such as the Iberian lynx Lynx pardinus or the imperial eagle Aquila adalberti (Delibes‐Mateos et al ., 2008 b ; Carro et al ., 2019).…”

Estimating Actual Abundance of European Sousliks: Using UAV Imagery, Pixel Based Image Analysis and Random Forest Classification to Count Souslik Burrows

“…This makes them important in maintaining ecosystem functions and services (Meadows and Meadows 1991;Hansell 1993;Whitford and Kay 1999;Haussmann 2017) including human health and well-being (Sandifer et al 2015;Brevik et al 2020). Several researchers (Davidson and Lightfoot 2007;Ewacha et al 2016;Lindtner et al 2019;Swaisgood et al 2019) have argued that their disappearance has contributed to the significant deterioration of natural grassland ecosystems and loss of related functions and services. However, due to their underground life-style and uneven activity patterns we know little about the dynamics of their population density and abundance (Johnson 1990;Butler 1995).…”

Cavity construction by reintroduced populations of Red‐cockaded Woodpeckers (Dryobates borealis)

“…Species reintroductions have become increasingly important for wildlife management. Habitat loss and fragmentation continue to isolate populations, lessen genetic exchange among populations, and jeopardize their persistence long term (Edwards & Costa 2004; Morandini & Ferrer 2017; Swaigood et al 2019). Translocation can be used to reintroduce species to areas where they have been extirpated as well as augment genetic resources in cases where small populations face a potential loss of genetic diversity (Griffiths et al 2017; Hale & Koprowski 2018).…”