victims are predominantly small cyprinids in nameless streams. It would be an 

 interesting luxury to explore this mystery. 



A special short-term threat to stream fauna are underground lines that require 

 in-stream digging or flow control. Habitat degradation from pipeline construction 

 was documented for a number of Michigan tributaries; impacts were limited to the 

 crossings and a few hundred feet below this point. '^ The study also recorded 

 beneficial effects when canopy removal resulted in thickening of bank vegetation. 

 Environmental variables and unknowns confounded the interpretation and signifi- 

 cance of other data in the report. 



Perhaps the brightest spot in an assessment of streams and transmission lines, from 

 the standpoint of research effort or ecologic understanding, is that we need not worry 

 about large streams or rivers. Their health is a product of a large complex watershed 

 in which transmission line impacts in this context all but vanish. 



Wildlife Habitat Impacts 



Most of what was learned came from non-ROW studies, such as those examining 

 the wildlife effects of commercial clear-cutting, selective-timber harvesting, or 

 controlled burning. Several investigations did focus on ROWs. Relevant studies of 

 small mammals and songbirds in diverse localities and habitats had this in common: 

 within a community some species are affected and some are not. Of those affected, 

 some are benefited and some are harmed. Populations often fluctuate independently 

 of treatment effects (e.g., clearing vs. control). Most measurements of these responses 

 were in terms of short-term population or habitat-use changes. Few investigations 

 ran for over eight years and sample sizes were often small. Nobody isolated 

 transmission line effects on a tagged population to discover significant cause-and- 

 effects events. Penetrating insight into these complex interactions is lacking, we only 

 observe nature in the gross. 



Most small mammal populations recover quickly from habitat perturbations; 

 severe perturbations retard the process. A frequently cited songbird study''' showed a 

 30 m ROW increased bird diversity, but a wide ROW (9 1 m) through forest decreased 

 it. The latter did attract several grassland species. It is puzzling why the narrow 

 corridor (12 m wide) lowered the index, for it too should have created a beneficial 

 opening in the canopy. 



Several investigators became curious about the barrier effects of ROW on 

 mammal movements. For example, Idaho deer and elk were not visibly hindered in 

 the fall of 1 974; '5 and 25 Blarina and /'fromv5fM5returned to their home range across 

 a ROW when artificially displaced by experimenters."" Evidence from snowshoe 

 hare,'^ deer,'** and tree squirrel'^ research suggests more interesting results might 

 come from an extensive study of the barrier and island-creating effects of 

 transmission corridors in snow country. Likewise, published (and casual) observa- 

 tions suggest that increased human use of some corridors may significantly alter 

 animal behavior and survival rates through hunting and vehicular disturbance. 2'^'"' 

 Such impacts can be mitigated by clearing selectively and leaving slash as cover. 22 



Significant local changes result when basic habitat alterations occur (as they often 

 do) — for example, when a grove of large mast and den trees are felled, or when severe 

 soil compaction or erosion destroys friable soils needed by fossorial species. Studies 

 continued to demonstrate edge-effects, mainly by species diversity indices. One 

 study" took a detailed look at how edge and shrub-cover controls the movements of 

 the rufous-sided towhee {Pipilo erythrophthalmus). It is not surprising that much 

 recent research supports what one might logically expect based on past research. 



Finally, in a major consultant-prepared report filed by a utility research 

 organization with a state agency, we learn: Site tfl "During the fall of 1975, two 

 woodchucks were seen on the ROW . . . They ran to their burrows upon approach. . . 

 Spring peeper activity was high off the ROW." Site #2 "... A swallowtail butterfly 

 was seen flying on the ROW at the time. Cottontail rabbit pellets were slightly 



214 



