The effect of human activities on the distribution and abundance of the Jordan Lake - Falls Lake bald eagles

I studied the effect of human activities on bald eagle (Haliaeetus leucocephahus) distribution and abundance at Jordan Lake and Falls Lake, North Carolina in 1986 and 1981. Eagles used most of the area available on Jordan Lake, but 63% of the use occurred in the northern 25% of the lake. Eagle use at Falls Lake was restricted to a few areas in the northern section of the lake. Jordan Lake had 1.2 times as many eagle observations as did Falls Lake. Data from radio-tagged eagles and timing of population fluctuations suggest that eagle populations at Jordan and Falls Lakes were principally migrating eagles from southern states. The peak in eagle numbers in May 1981 may have represented a migratory wave, whereas the decrease in June and July may have been the result of some eagles continuing northward. Eagles returning south from the Chesapeake Bay and other northern areas may account for the slight increase observed in August. Two eagle roosts were located and monitored throughout the study at Jordan Lake. Human activities at both lakes peaked during summer months. Boating was the predominant activity during summer. Sixty-three intentional disturbances by motor boats produced a mean eagle flush distance of 131.2 m. Only 8% of the eagles flushed when the approaching boat was > 250 m from shore. Loglinear analysis revealed that human use of the shoreline and eagle use of the shoreline were related. Shoreline segments (250 m) used by humans were used less frequently by eagles than would be expected under a model of complete independence. I saw more eagles and fewer humans on weekdays than on weekends during boat surveys of selected Jordan Lake sections, suggesting that human use in certain sections on weekends displaced eagles. The lake section north of the Farrington Bridge showed the largest difference between eagle numbers on weekdays versus weekends. I developed a regression model that predicted the threshold density of disturbance Within this section to be 0.5 boats/km². On most days during the summer, this threshold level of boating traffic is surpassed in lake sections south of the Farrington Bridge. Primary management objectives should be to reduce human activities within high-eagle use areas, specifically the northern end of Jordan Lake, and to promote the bald eagle as a recreational benefit rather than a management problem.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Fisheries and Wildlife Sciences

Department dc:contributor.department

Fisheries and Wildlife Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1988

Author dc:creator

• Smith, Timothy John

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-10132010-020311

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/45186