Can Golf Courses Be Designed To Enhance Amphibian 
Diversity on Golf Courses? :
Effects of Turf on Amphibian Movements

2000 Final Report
1 November 2000
Dr. Peter Paton

Assistant Professor, Department of Natural Resources Science, University of Rhode Island, Kingston RI 02881

Research Objectives:
    (1) Compare immigration and emigration rates of two age cohorts (adult and metamorphs) of           pond-breeding amphibians across a forested landscape fragmented by turf.
    (2) Assess the effect of grass height on amphibian movements.
    (3) Assess amphibian use of experimentally created travel corridors.
    (4) Quantify amphibian community structure at golf courses throughout southern New England.
    (5) Monitor changes in amphibian population size at a breeding pond following construction of a
         golf course.

Recent research on movements of pond-breeding amphibians across fragmented landscapes in New England is equivocal and mainly focused on post-breeding dispersal by metamorphs (recently transformed young-of-the-year). I monitored immigration and emigration rates of pond-breeding adult and metamorph amphibians across a forested landscape fragmented by commercial turf fields. I captured 7,122 amphibians in 42,566 trapnights from May 1998 to June 2000. Daily capture rates and daily species richness estimates were >2.2 times greater in forest-interior compared to forest-turf edge; both habitats were approximately 125 m from the same breeding ponds. Adults of 2 species, green frog (Rana clamitans) and pickerel frog (R. palustris), readily immigrated across a 68-m wide turf field to reach breeding ponds, while turf filtered movements by adults of 6 other species (wood frog [Rana sylvatica], spring peeper [Pseudacris crucifer], gray treefrog [Hyla versicolor], American toad [Bufo americanus], spotted salamander [Ambystoma maculatum], red-spotted newt [Notophthalmus viridescens]). Movements by metamorphs were less affected by forest fragmentation than adults. Capture rates of metamorphs of 4 species (green frog, pickerel frog, spotted salamander, red-spotted newt) were equivalent in forest-interior and forest-turf edge, whereas metamorphs of 4 species were 5 (American toad) to 165 (spring peeper) times more abundant in forest-interior compared to forest-turf edge. These results indicate that most pond-breeding amphibian species in southern New England are habitat specialists during at least one stage of their complex life cycle, adults tend to be greater habitat specialists than metamorphs, and forest fragmentation is affecting dispersal by amphibian populations in the region.
Experimental evidence found that frogs preferred to move through wooded habitats rather than turf (P = 0.058) or barren areas (P = 0.002). This suggests that dispersal corridors from ponds to upland wintering areas should be forested habitats. Therefore, we created a series of experimental forested travel corridors during the 2000 field season. Contrary to our initial findings monitoring movements across a fragmented landscape, adults of most species showed no preference for the corridors, while metamorphs of most species were more likely to use travel corridors than cross open habitats.

Surveys of 59 ponds at 32 golf courses in southern New England found that Green Frogs and Bullfrogs dominated most of the ponds (e.g., found in 73% of the ponds surveyed) at golf courses in the region. This is because these species prefer water bodies that are permanently flooded, as their tadpoles take 1-3 years to undergo metamorphosis and disperse from the pond. In contrast, the young of other species of pond-breeding frogs and salamanders only remain in the pond for less than 6 months, and their young are out competed by Green Frog and Bullfrog. A simple management solution may be to modify the hydroperiod length of a pond to increase species richness.

Finally, from 1997 to 2000, we monitored amphibian community structure in a vernal pond, which had a golf course constructed 150 m west of the pond during the summer of 1999. During baseline years (1997-1998), we detected 11 species of amphibians, while post-construction we detected 10 species. In general, population sizes of adults did not fluctuate dramatically following golf course construction, with the exception of Wood Frog, Marbled Salamander, and Red-backed Salamander. The only species that appeared to have declined as a result of golf course construction was Marbled Salamander. However, Marbled Salamander migration coincided with construction of a road 20 m from the pond in Aug-Sept 2000 to a small housing development. Therefore, it was difficult to separate the effects of road construction from golf course construction. In addition, amphibian populations often undergo dramatic population fluctuations in undisturbed ponds.
In summary, our research suggests that amphibians can be sensitive to habitat fragmentation, many species prefer to disperse through forested habitats rather than turf habitats, manipulating grass height does not appear to enhance amphibian movements through an area, and it was difficult to detect any obvious indication of changes in amphibian community structure when a golf course was constructed 150 m from a breeding pond.