tahoemonitoring.org

  • Increase font size
  • Default font size
  • Decrease font size
Home Land Upland Species and Communities

Deer

Status and Trend

Interpretation and Commentary

DEER


Click to interpret this icon

Status: No Established Target
Trend: Moderate Improvement
Confidence: Moderate

 

  • Relevance - Mule Deer (Odocoileus hemionus) are of exceptional value to the public for wildlife viewing and hunting. Deer can be found in the Tahoe Basin during the summer and typically migrate to lower elevation areas with less snow for the winter (DFG 2006). The spring and fall counts indicator measures the total number of deer counted during post-hunt (fall) and spring aerial surveys in the vicinity of the Tahoe Basin (Nevada hunting units 192, 194, and 196). The counts are an indicator of deer abundance in the Tahoe Basin. This indicator provides information on trends in deer populations, but does not provide information on the total number of deer in the Tahoe Basin, which may be higher or lower than the numbers presented here.
  • Adopted Standards  - No Threshold Standard has been adopted for the spring and fall deer counts indicator. This indicator provides information relevant to the adopted Management Standard requiring maintenance of all fawning habitat in the Tahoe Basin.
  • Indicator - Total number of deer observed during spring and post-hunt aerial surveys in Nevada hunting units 192, 194, and 196.
  • Attainment Status – No target has been established for the fall and spring deer counts. Since 1989 the total number of Deer observed during the combined spring and post-hunt counts has fluctuated between 540 and 4128 individuals. The long-term (1989-2010), and five year (2006-2010) average number of deer observed are 1835 and 1349, respectively.
  • Trend –  Two distinct trends are evident. From 1989 – 1999, a linear regression showed a statistically significant (P = 0.04, R2 = 0.38) decreasing trend in the number of deer detected. The trend appears to have reversed direction, and from 2000 to 2010, a linear regression showed a statistically significant (P = 0.01, R2 = 0.54) increasing trend.

Click here for more information...

  • Confidence  - There is a low level of confidence in the reliability of the survey data. Data arecollected by qualified wildlife biologists following standard protocols. However, since 2006 the post-hunt surveys have been conducted slightly later, which may allow a greater portion of the herd to migrate into the study area and increase the number of observations (NDOW 2007). This change in survey timing reduces the confidence in making long term comparisons of the data. There is, however,a high level of confidence in the existence and direction of the trends because there is little scatter of yearly points (counts) around the regression line after 1995. The overall confidence in the status and trend is medium.
  • Human and Environmental Drivers - The previous declining trend in the deer population was likely due to wintering habitat loss and fragmentation in areas outside the Tahoe Basin (NDOW 2010; Wildlife Action Plan Team 2006). This decline coincided with population declines throughout Nevada (Wasley 2004). The more recent increasing trend in the deer population could be the result of targeted habitat improvements implemented by public agencies (Wildlife Action Plan 2006; NDOW 2006), and/or a general decrease in the rate of development in recent years. TRPA has not permitted projects that would reduce the availability of fawning habitat, or reduce the connectivity of known migration corridors within the Tahoe Basin, so changes in habitat conditions in the Basin were not a likely driver of either trend.
  • Monitoring Approach – Biologists from the Nevada Department of Wildlife and the California Department of Fish and Game perform a combination of line transect and directed search aerial surveys to record the total number of deer observed and categorize them by age and sex. The surveys include a post hunting season (fall) survey in December or January, and spring survey in March. Only a small portion of these surveys occur within the eastern portion of Tahoe Basin, but these surveys document migratory herds, some of which enter the Basin for portions of the year.
  • Monitoring Partners – Nevada Department of Wildlife and the California Department of Fish and Game.

Links

 
  • Monitoring Plan
  • Conceptual Model

Map

click map for larger image

Suitable mule deer fawning and forage habitat (summer) in the Lake Tahoe Region.

Trend Charts

Chart data not available at this time.
 

Additional Info

References

  1.  
  2.  
  3.  

Additional Information

  1.  
  2.  
  3. Conceptual Model:
  4. Monitoring Plan:
Last Updated on Wednesday, 07 November 2012 11:02