Vol. 24, Wo. 2 
Page 3 
Responses of P raf rie Chicken to Habi tat Hani pu lati on- W-66-R R. L. Westemeier, 
J.E. Buhnerkempe 
Since 1973, declines in the prairie chicken population at Bogota were 
related to high rates of nest predation, declining hatchab i 1 i ty, reduced nesting 
effort, and the adverse impact of the ring-necked pheasant (Ml/RL 19(3) :3-4, 
22(9) :3, 23(12) :3, 24(1):4). Another factor that may be impacting negatively 
on the Bogota flock is public visitation during booming season. 
Over the past 15 years, a total of 4,544 visitors (including repeaters) 
spent 731 blind mornings observing the courtship ritual of the prairie chicken 
on booming grounds (leks). Data for these 15 years showed no significant 
correlations between the number of known disturbances by human and natural 
factors (£ * -0.483), or the number of blind mornings (r_ = -0.492), and the 
number of nests found per hen seen on leks. Over the past 5 years, however, we 
have noted a relationship that may be cause for concern. In 1976 and 1973, the 
number of nests found per hen observed on leks at Bogota was high, whereas the 
number of blind mornings was relatively low (Table 1). Conversely, the years 
when the number of nests per hen was low (1977 and 1980), the number of blind 
mornings was high. The number of known instances that humans flushed birds per 
blind morning was stable from year to year, so the amount of human disturbance 
was related to the number of blind mornings for a given spring. 
Booming prairie chickens are disrupted not only by humans but by avian 
predators, pheasants, and mammals. When the number of incidences of flushed 
birds per morning due to natural causes exceeded 1.0, the number of nests per 
hen dropped to low levels (Table 1). 
The combination of prolonged bad weather (rain and high winds), persistent 
harassment by harriers and pheasants, and disturbances by the visiting public 
may be sufficient some years to delay or prevent mating and thus limit the 
nesting effort. We can do little about natural factors, but we can and should 
increase supervision and guidance of visitors. This spring we hope that the 
following changes will reduce disturbance to prairie chickens on their booming 
grounds: 
1. Reduce the limit on observers from 20 to 10 per morning. 
2. Alternate blind mornings among booming grounds. 
3. Allow visitation only on 2 or 3 mornings per week instead of almost 
every morning. 
4. Place more emphasis on blind etiquette, rules, and regulations. 
