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The painted turtle, Chrysemys picta Schneider (family Emydidae), has been divided into four subspecies (with differing morphological characteristics), two of which intergrade in the northeastern United States. The intergradation of C. p. marginata (midland painted turtle) and C. p. picta (eastern painted turtle) has been well studied in some areas, but has been poorly studied in Vermont, an area that could contribute important information on this species and the process of intergradation. Turtles were trapped and released from three different watersheds in Vermont, and others were examined from collections at the Carnegie Museum of Natural History from within the center of the ranges of the two parent subspecies to investigate the hypotheses that Vermont's turtles are intergrades, and that the amount of influence from each subspecies differs with drainage in Vermont. For the external characteristics of scute disalignment, scute border width, and plastral figure, many of Vermont's turtles were determined to be significantly different from typical marginata and picta, and were intermediate to them, strongly suggesting that they are intergrades. Samples from the southeast corner of the state were determined to be picta.
Experimental field studies at two sites in Long Island Sound have demonstrated that the nonindigenous Asian shore crab, Hemigrapsus sanguineus deHaan 1853, is a highly mobile grapsid crab that shows limited fidelity to a particular shelter or feeding site. Recovery rates of tagged crabs differed significantly at the two sites, but no differences in site fidelity were measurable between males and females at either site. Between-site differences in percent crabs recovered may be due to differences in food and shelter availability at the two sites. There is some suggestion that familiarity with a shelter site may influence site fidelity by leading to reduced mobility. A conservative estimate (based on recovered crabs only) of the mean distance traveled in 24 hours (n = 38) was 7.43 ± 1.54 m; among those crabs recovered a distance > 5 m from the release point (n = 15) the mean distance traveled was 16.87 ± 2.23 m. The rapid, widespread dispersal characteristic of the Asian crab invasion along the east coast of the United States may be due in part to the high adult mobility and low site fidelity exhibited by H. sanguineus.
We examined the correlation between canopy gap formation and the initial growth of forest trees by reconstructing the gap history of a Tsuga canadensis (L.) Carr. forest community in southeastern Ohio. We cored each tree (>10 cm dbh, n = 156) in a 40 × 90 m plot and examined the cores for release events, characterized by dramatic increases in radial growth. We identified 80 former gaps in the 79 yr sample period by clustering release events in time and space. Thirteen of the 80 former gaps coincided with the initial growth of trees. These 13 gaps were usually large gaps containing few established trees or gaps undergoing repeat disturbance. Of the 36 trees >10 cm dbh that began growth during the sample, 21 (58%) began growing inside a gap within 6 yr of gap formation-three times the rate predicted by chance (p = 0.001). We also measured the distance in time and space between the first year of growth and the closest canopy gap for each tree. We called the inverse of this measure the gap affinity index (GAI). Although we did not find significant differences in GAI among species, the index confirmed qualitative notions about the shade tolerance of six common tree species: intolerant species exhibited high gap affinities, while tolerant species exhibited low gap affinities. We also found a significant, positive correlation between GAI and the area of the closest gap, as well as a significant, negative correlation between GAI and the mean number of releases per species.
Wheeler Marsh in Milford, Connecticut provides habitat for diamondback terrapins (Malaclemys terrapin), a unique estuarine turtle. To assess potential prey availability, the distribution and abundances of marsh snails (Melampus bidentatus), mud snails (Ilyanassa obsoleta), marsh mussels (Geukensia demissa), and fiddler crabs (Uca spp.) were studied in several sub-habitats (marsh surface, marsh edge, creek bank, and mudflats) of five tidal creeks. Almost all terrapins have been found in one section of the marsh, Turtle Creek, where all four prey species were present in large numbers. However, high numbers of some prey were found in other sections of the marsh as well, suggesting that resource availability may not be the primary determinant of terrapin distribution. The physical structure, plant density, and tidal amplitudes of salt marsh creeks may also be important determinants of terrapin distribution via their influence on resource accessibility.
The nesting behavior of >300 females of Oxybelus bipunctatus was studied for 15 straight weeks in a sandpit in central New York during late spring-summer 1985. Cool and rainy weather in late spring induced moldy conditions in the cells that caused much larval mortality. Successive generations of wasps emerged in the field and laboratory every four to six weeks. Cells were always excavated in moderately damp sand. Cell depth varied inversely with soil moisture as tied to the amount of rainfall. Female cocoons were larger and heavier than male cocoons, but they did not occupy deeper or shallower cells. One-celled nests were predominant in this species. The number of prey per cell was rather uniform throughout the nesting season despite much variation in the prey fly families. Individual and aggregate prey weight per cell decreased slightly through the summer. Male Cyclorrapha were preyed upon more than any other taxon.
For Cicindela puritana to be a viable member of New England's biota, there must be more than the current two occurrences. Assessment of the chance that the species can spread, whether on its own or through reintroduction, required identifying vacant habitat patches, which in turn, required refining the description of the species' larval habitat. Analysis of larval microhabitat variables identified sand texture as the most important determinant of habitat suitability. I then surveyed a 79 km stretch of the Connecticut River in Connecticut looking for suitable habitat patches. Of 32 beaches, none that appeared to be suitable was nearer than 12 km from currently occupied patches. Dispersal is unlikely to lead to establishment of new populations, so I recommend reintroducing C. puritana to an area in the vicinity of Windsor, CT where there are beaches on three islands that appear to be suitable larval habitat.
A brief review of the taxonomic history and integrity of selected North American branchiobdellidans is given to clarify their current status. The zoogeographical distribution of branchiobdellidans on the North American continent is presented based on published reports and information in the Catalog of the National Museum of Natural History, Smithsonian Institution, Washington, DC. These data are tabulated by species with locations referenced to zoogeographical subregions, political units of provinces, states, or countries, and source citations. Distributional anomalies of certain taxa are discussed.