Eastern Fox Squirrels in the West

Jennifer K. Frey1, Pedro Casllo1, Jaime Iglesias2 1New Mexico State University, Las Cruces, NM 2Texas A&M Agrilife Extension Service, El Paso, TX Nave Distribuon of Pecans • Pecans are nave to south-central USA • Western pecan growing region has ideal climate and few nave wildlife pests

Western pecan growing region

Distribuon of commercial Nave distribuon of pecans pecan producon Ground squirrels

• Ground squirrels – Ubiquitous in West – Main nave wildlife pest in western pecan growing region Rock squirrel • Nave species (Otospermophilus variegatus) – Rock squirrel – California ground squirrel

California ground squirrel (Otospermophilus beecheyi) Ground squirrels • Can climb trees • Live in burrows in ground – Flood irrigaon usually prevents living in orchard – Burrows usually located along edge, especially along irrigaon canals Ground squirrels can climb trees

Irrigaon floods burrows in orchards Ground squirrels live in burrows along edges Ground squirrels

• Legal Status – Non-game species – recognized agricultural pest • Numerous control opons – Traps – Fumigants – Toxicants (legal method for ground squirrels) – Deploy at burrows around edges of orchards where they live Ground squirrels • Relavely minor damage to western pecan producon • Do not live inside the orchards • Damage mostly by removal of nuts from edges of orchards • Numerous control opons available EASTERN FOX SQUIRREL A NEW (AND MORE SERIOUS) PROBLEM…. Comparison Fox squirrel & Ground squirrel If in doubt of idenficaon, take photograph or dead animal to game and fish or local university for idenficaon

Eastern Fox Squirrel Ground Squirrel Nave gray squirrels •Overall orange; tail very bushy •Overall gray; moled white •California and Arizona only •Lives in trees spots •Overall gray, bushy tail, no •Runs to trees when frightened •Lives in burrows moling •Runs to burrows when •Lives in trees frightened •Not usually problem in pecans Eastern Fox Squirrel

• Nave to eastern USA

Eastern Fox Squirrel (Sciurus niger) Nave Distribuon Eastern Fox Squirrel Eastern Fox Squirrel

• A true “Tree Squirrel” • Nave to eastern Oak- Hickory Forest – Evolved with pecan and other related trees Nave distribuon of eastern fox squirrel

Distribuon of Hickories (Carya) Nave distribuon of pecans (Carya illinoensis) Introduced Eastern Fox Squirrel • California – Mulple introducons start 1904 – Expanded 4 miles per year – Present in numerous pecan growing regions • Arizona Introduced Eastern Fox Squirrel – No fox squirrels Populaons • New Mexico – Pecos Valley • Introduced prior 1958 • Widespread – Llano Estacado • Addional introducons (Frey and Campbell 1997) – Rio Grande — No fox squirrels yet! • Texas – Trans-Pecos region – Rio Grande El Paso Valley Western Pecan • Introduced ca 2000 (Frey et al Growing Region 2013) • Widespread • Mexico--unknown Dispersal ability

• Dispersal Characteriscs – Adult females defend core area; Mesilla Valley- force young to disperse No Squirrels – 40 mile – maximum dispersal distance (Allen 1943) – Does not require trees • Result 25 miles – Connually expanding distribuon – Mesilla Valley at high risk of invasion by eastern fox squirrels El Paso Valley- Squirrels DAMAGE TO PECAN ORCHARDS

Eastern Fox Squirrels in Western Pecan Orchards • Eastern fox squirrels spend enre lives in the orchard, living in the trees • Obtain all food and shelter from the pecan trees • Lile informaon on extent of damage and ways to control

Eastern Fox Squirrel eang green pecan Types of Damage

• Consumpon flowers and buds • Limb/twig cung • Nest excavaon • Nuts 3 leaf nests in one tree – Scaer-hording – Full & paral consumpon • Bark stripping Damage

• Consumpon of flowers/buds – Spring – No damage esmates • Limb/twig cung – Consume twigs – Harvest nuts – Construct nests Fox squirrel eang maple buds – No damage esmates • Cavity nest excavaon – Enlarge holes caused by other things – No damage esmates

Young fox squirrels in cavity nest Damage: Nuts

• Huggins (1991) study-damage in nave pecans groves, Oklahoma – More pecans lost to damaged by wildlife than were harvested • Consumpon – 37 pounds/acre • Scaer-hording – bury nuts for later use – 59% of pecan losses due to wildlife – 101 pounds/acre • Squirrels might select highest quality nuts Damage: Bark Stripping

• Possibly the most important source of damage (Kenward 1983) – Kill branches – Weakens branches; may break – Allow diseases access, which can impact/kill tree • Most probably occurs late Winter • Might target fastest growing limbs • Why (theories) – Use inner bark as food – Access water – Territorial marking at high densies Bark Stripping

• Our Results – Significantly more bark stripping in trees with nests • No nests: mean 5 strips • Nests: mean 35 strips – Significantly more bark stripping in larger (older) trees

MANAGEMENT OPTIONS

Fox Squirrel Control • Non-lethal--No proven methods – Tree baffles – Electric fence – Repellents – Scare devices • Lethal – California • “Eastern fox squirrels found to be injuring growing crops or other property may be controlled at any me and in any legal manner by the owner or tenant of the premises without a permit.” – Texas and New Mexico • Protected game species • Must obtain depredaon permit – Methods • Traps, guns • No legal toxicants • Federal Assistance—USDA Wildlife Services – Call 1-866-4USDAWS Control likely to be difficult

• Goal: eradicate fox squirrels from west Texas and New Mexico • Compensatory mortality (Nixon et al. 1974, 1975) – Fox squirrel populaons can withstand removal of 40% of resident squirrels – Fox squirrel populaons can withstand removal of 80% of resident squirrels, if there is immigraon of new squirrels • Dispersal – Connual influx of new animals into areas with control – Expansion of squirrels to new areas

As a control method, hunng would need to be intensive and connual; not likely to be effecve Recommendaons

• Goal: Eradicate fox squirrels from pecan producing regions of western Texas and New Mexico where the species is non-nave • Prevent spread to new area, especially Rio Grande in New Mexico • Change status of eastern fox squirrels in New Mexico and western Texas to allow unlimited lethal control • Research! – Extent of damage – Methods to reduce damage – Methods to eradicate and prevent spread Acknowledgements

• Funding – Dr. Martha Desmond Natural Resource Career Track Program • Informaon – Jim Stuart, New Mexico Department of Game and Fish – Dave Morrison, Texas Department Wildlife and Parks • Access and Logiscal support: – MBM Farms (Fabens), especially Marcelino Lozano and Jerry Toca – 5R Farm (Tornillo), especially Oscar Eribes – Hermanos Brown Farm (Socorro), especially Wesley Stubbs Thank you

Fox squirrel eang cherry blossoms

Management of Ground Squirrels

• Characteriscs – Recognized as agricultural pests – Non-game species in most states (i.e., legal for residents to kill with traps or firearms) • Focus control at burrows – periphery of orchards, especially irrigaon canals Management of Ground Squirrels Toxicants • Zinc phosphide treated grain – Restricted use pescide (can only be applied by licensed pest control operators or those with private applicator license) – Not highly palatable • Must prebait with untreated grain to encourage use before applying treated grain • Only apply treated grain if untreated prebait is readily consumed • Apply bait to burrow opening • Ancoagulat baits (e.g., diphacinone) – More expensive and require mulple feedings – Can be applied by hand or used in bait boxes for connuous supply – Aversion can develop if squirrel become ill but does not die Management of Ground Squirrels Other • Burrow fumigants – Overall more labor intensive and expensive than toxicants – Gas cartridges • Easy and readily available – Aluminum phosphide tablets • Restricted use pescide • Non-lethal methods – none proven effecve for orchards