36. 
37. 
38. 
for an observed decline in a Montana 
bighorn sheep population are human 
disturbance and harassment of sheep. 
Snowmobile use of an important segment 
of sheep winter range is increasing. 
It is suggested that harassment may be 
debilitating to winter-stressed ani- 
mals. 
OFF-ROAD VEHICLES, HARASSMENT, FORESTS, 
RANGELAND, WILDLIFE MANAGEMENT, U.S. NA- 
TIONAL FORESTS, BIGHORN SHEEP 
Bird, D. M. 1978. Birds of prey: A 
plea for ethics. Ont. Nat. 17(5): 16- 
23. 
Problems facing birds of prey are de- 
scribed in this nontechnical article. 
Effects of man on raptors are discus- 
sed, including impacts of research, 
wildlife photography, and bird watch- 
ing. Disturbances of birds by these 
activities can cause adults to abandon 
nests, and decrease survival of eggs 
and young through predation or expo- 
sure. Education of the public on the 
values of birds of prey is essential 
for their protection. 
HIKING, CAMPING, BOATING, HARASSMENT, 
RESEARCH IMPACTS, WILDLIFE VIEWING, PRE- 
DATION, THREATENED AND ENDANGERED SPE- 
CIES, RECREATION MANAGEMENT, RAPTORS 
Blodget, B. G. 1978. The effect of 
off-road vehicles on least terns and 
other shorebirds. Univ. Massachu- 
setts, Amherst, Natl. Park Serv. Coop. 
Res. Unit Rep. 26. 79 pp. 
The impact of off-road vehicles on a 
nesting colony of least terns and oth- 
er migratory shorebirds was studied on 
outer Cape Cod, Massachusetts. Fenc- 
ing of colonies reduced vehicle dis- 
turbance of nests. Frequent distur- 
bance by vehicles and beachwalkers did 
not appear to cause nest abandonment 
or reduced hatchability of eggs. Man- 
agement recommendations are developed 
based on these results. 
HIKING, OFF-ROAD VEHICLES, 
ZONES, RECREATION MANAGEMENT, 
MANAGEMENT, U.S. 
TERN, WATERBIRDS 
COASTAL 
WILDLIFE 
NATIONAL PARKS, LEAST 
Blokpoel, H. 1981. An attempt to eval- 
uate the impact of cannon-netting in 
Caspian tern colonies. Colon. Water- 
birds 4:61-67. 
10 
39. 
40. 
4l. 
From studies of Caspian terns on Lake 
Huron, Ontario, it was found that vis- 
its to tern colonies resulted in 
losses of eggs to predation by gulls. 
Human activities at tern nesting colo- 
nies should be restricted until more 
is known about the nature and extent 
of human-induced nest losses. 
DISTURBANCE (GENERAL), RESEARCH IMPACTS, 
LAKES, WILDLIFE MANAGEMENT, PREDATION, 
CASPIAN TERN 
Blong, B. 1967. Desert bighorn and 
people in the Santa Rosa Mountains. 
Pages 66-70 in J. Yoakum, B. Browning, 
R. Miller, and A. S. Leopold, eds. 
California-Nevada Section, The Wild- 
life Society, 1967 Transactions. 14th 
Annual Meeting, 27-28 January 1967, 
Disneyland, Calif. California-Nevada 
Section, The Wildlife Society, Reno, 
Nev. 
Loss of habitat in California through 
human encroachment is described as a 
serious threat facing bighorn sheep. 
Disturbance by hikers and picnickers 
caused sheep to abandon a key water- 
hole. Other sources of potential dis- 
turbance had no apparent effect on 
sheep. 
HIKING, HORSEBACK RIDING, PICNICKING, 
WILDLIFE VIEWING, DESERTS, BIGHORN SHEEP 
Boeer, W. J. 1977. Riparian mammals in 
Big Bend National Park and their in- 
terrelationships with visitor usages 
and impacts. M.S. Thesis. Texas A&M 
University, College Station. 122 pp. 
Small mammals of the riparian corridor 
of the Rio Grande were inventoried and 
jmpacts on the corridor of increased 
human use were evaluated. Subjective 
impact evaluation data provide park 
managers with a way of monitoring fu- 
ture impacts. 
BOATING, CAMPING, DESERTS, RIVERS, REC- 
REATION MANAGEMENT, U.S. NATIONAL PARKS, 
MAMMALS 
Boeer, W. J., and D. J. Schmidly. 1977. 
Terrestrial mammals of the riparian 
corridor in Big Bend National Park. 
Pages 212-217 in Importance, preserva™ 
tion and management of riparian habi- 
tat: A symposium. 9 July 19/7, Tuc~ 
son, Ariz. U.S. For. Serv. Gen. Tech. 
Rep. RM-43. 
