Gunnison’s Prairie Dog Use of Resource Pulses in a Chihuahuan Desert Grassland at the Sevilleta National Wildlife Refuge, New Mexico: Re-sight Scan Data

Seasonal environments experience cyclical or unpredictable pulses in plant growth that provide important resources for animal populations, and may affect the diversity and persistence of animal communities that utilize these resources. The timing of breeding cycles and other biological activities must be compatible with the availability of critical resources for animal species to exploit these resource pulses; failure to match animal needs with available energy can cause population declines. Adult Gunnison’s prairie dogs emerge from hibernation and breed in early spring, when plant growth is linked to cool-season precipitation and is primarily represented by the more nutritious and digestible plants that utilize the C3 photosynthetic pathway. In contrast, summer rainfall stimulates growth of less nutritious plants using the C4 photosynthetic pathway. Prairie dogs should therefore produce young during times of increased productivity from C3 plants, while pre-hibernation accumulation of body fat should rely more heavily upon C4 plants. If seasonal availability of high-quality food sources is important to Gunnison’s prairie dog population growth, projected changes in climate that alter the intensity or timing of these resource pulses could result in loss or decline of prairie dog populations. This project will test the hypothesis that population characteristics of Gunnison's prairie dog, an imperiled grassland herbivore, are associated with climate-based influences on pulses of plant growth.季节性环境中，植物生长会呈现周期性或不可预测的脉冲式变化，为动物种群提供关键资源，并可能影响利用这些资源的动物群落的多样性与存续能力。动物物种的繁殖周期及其他生命活动的节律必须与关键资源的可获得性相匹配，才能有效利用这些资源脉冲；若动物的需求与可获取的能量无法适配，则会导致种群数量下降。成年Gunnison草原犬鼠（Gunnison's Prairie Dog）会在早春结束冬眠并开始繁殖，此时植物生长与冷季降水相关，优势物种为利用C3光合途径（C3 photosynthetic pathway）、营养价值更高且更易消化的植物。与之相对，夏季降雨会刺激利用C4光合途径（C4 photosynthetic pathway）、营养价值较低的植物生长。因此，草原犬鼠应在C3植物生产力提升的时段产仔，而冬眠前体脂的积累则更多依赖C4植物。若优质食物来源的季节性可获得性对Gunnison草原犬鼠的种群增长至关重要，那么预计会改变这些资源脉冲强度或发生时间的气候变化，可能会导致草原犬鼠种群的减少或衰退。本项目将验证这一假说：作为一种濒危草原植食动物，Gunnison草原犬鼠的种群特征与气候因素对植物生长脉冲的影响存在关联。