(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
(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
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.