How Disturbance Impacts Wildlife By Lauri Turner, Forest Wildlife Program Manager, Deschutes National Forest, Supervisor’s Office, lturner@fs.fed.us

Direct Effects Death or Injury Habitat Loss From collisions Could have population level changes if dealing with low density populations Habitat Loss Direct loss of habitat due to road and/or trail construction

Indirect Effects – Habitat Degradation Increased compaction – may reduce vegetation, not allow burrowing into soil, etc. Trampling of Vegetation Spread of Invasive Species Bare ground allows invasives to get a foothold Tires can serve as a vector for spread

Habitat Degradation Increased sedimentation potential Roads and trails within riparian reserves serve as sedimentation sources Especially where there are social trails to the river/stream’s edge Loss of habitat components like snags and down woody material Hazard trees cut along system roads and trails Taken as firewood

Habitat Degradation Garbage Dogs Can lead to habituation to humans Can lead to health problems for animals Dogs Chasing animals can reduce energy reserves and if caught may result in injury or mortality Could spread disease

Habitat Quality - Disturbance Wildlife Displacement Displaces animals either temporarily or permanently Flushing animals when present – interrupts foraging, causes increased energy expenditures, etc May cause nest abandonment Habitat Avoidance Lower population densities near roads/trails Example – Ryan Ranch Key Elk Area Elk avoid Ryan Ranch and the Deschutes River during the daytime due to human presence – have shifted use to nighttime

Habitat Quality - Disturbance Acute or chronic physiological damage (i.e. hearing loss) If subjected to loud noises (above ambient noise levels – i.e. ATV or motorcycle use), some species have experience hearing loss This can lead to increased predation potential, unable to hear mating calls, etc. Increased energy expenditures Usually results from being flushed (i.e. deer along roadside) Compounded if it occurs during a high energy need period (i.e. winter, feeding young)

Habitat Quality - Disturbance Physical injury due to panicked responses Interference with normal activities (i.e. feeding, breeding) Noise may emulate natural sounds and cause inappropriate effects (i.e. emerging during the wrong season) Impaired communication among individuals or groups Human-made noise interferes with animal communication signals, sounds animals listen for orientation, and predator-prey detection Interferes with ability to capture prey

Habitat Quality - Disturbance Increased stress hormones Leads to reduced reproductive success Altered behaviors Shifting periods of use Using lower quality habitat Aggression Altered nest/den placement

Connectivity and Barriers High landscape connectivity is a landscape that has few barriers and where animals can move freely – moving through different habitats in order to meet daily and life needs High landscape connectivity allows for movements to re-populate areas and minimizes inbreeding

Connectivity and Barriers Barriers can be a variety of things depending on the species Examples include unsuitable habitat, roads/trails, waterways, urban areas, etc. Barriers that impede movement result in higher mortality, lower reproductive success, and smaller populations Isolation caused by barriers to movement can reduce gene flow leading to genetic effects

Fragmentation Fragmentation Decrease some habitat type in a landscape OR Apportionment of habitat into smaller, more isolated patches Roads and trails result in large patches being dissected into smaller patches Reduces interior forest habitat and increases edge effect Long and linear = more edge habitat Impacts are not all equal – areas with high diversity (i.e. riparian habitats) may experience greater impacts