Richard Stevens

Deer mouse preference for seed of commonly planted species, indigenous weed seed, and sacrifice foods.

Highlight: Captive deer mice from pinyon-juniper, sagebrushbitterbrush, and Jeffrey pine-ceanothus plant associations were fed a variety of shrub, grass, forb, and tree seeds. Mice ate or destroyed an amount of seed equal to approximately one-third their body weight daily. Seed of bitterbrush, singleleaf pinyon, balsamroot, and small burnet were the most preferred food items tested while seed of Utah juniper, smooth brome, fourwing saltbush, and big saltbush were least preferred. Planting valuable forage species whose seeds are not preferred by deer mice would appear to improve seeding success on sites where seed predation by deer mice is a problem.

Deer mouse consumption of bitterbrush seed treated with four repellents.

Bitterbrush (Purshiu tridentata) seeds were treated with one of four repellents-Mestranol, R55, Red Squill, or Alphanaphthylthiourea (ANTU)-and offered to caged deer mice (Perom_vscus maniculatus). ANTU reduced deer mouse consumption of bitterbrush seed the most (up to 90%) and was not toxic to germinating seed. Deer mice consumed even less ANTU treated seed when seed was first soaked in a 3% thiourea solution to hasten germination. Although ANTU did not reduce seed consumption of treated bitterbrush seed (a 2: 55 seed consumed/mouse/night) as much as 0.5% or 1% Endrin (3 = 35-29 seed consumed/mice/night), this may not be relevant as Endrin is banned in Canada and subject to severe use restrictions on federal lands in the United States.