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We studied the activity of 11 and movement of 6 radio-tagged eastern coyotes (Canis latrans var.) inhabiting suburban Cape Cod, MA between June 1998 and August 2001. Coyotes were nocturnal year round except for breeding females, which were active day and night during April–June. Twenty four-hour movements of coyotes ranged up to 31.9 linear km and averaged 23.5 ± 7.3 (SD) km from 5–14 radio-fixes during each 24 hr monitoring period. There was no difference between male and female movement rates. Coyotes moved through altered open areas more than expected when compared to residential and natural areas. Coyotes inhabiting urbanized areas generally use residential areas for traveling and/or foraging.
We studied nest site selection by Eastern Wild Turkeys (Meleagris gallopavo silvestris) to compare successful and unsuccessful nests at the northern edge of the species' range in central Ontario during 2000. Six of 16 (38%) nests that we studied were successful. Successful nest sites had greater percent vertical obstruction than unsuccessful nest sites. However, both percent vertical and horizontal obstructions were the best predictors of nest success, suggesting that no single set of habitat characteristics may offer protection from a diverse predator community.
Fishes were collected in all four streams of the Presque Isle Bay watershed in Erie, PA, to assess the environmental effects of urbanization. These streams were evaluated using an index of biotic integrity (IBI) combined with a multivariate analysis. Four reference streams in adjacent non-urban watersheds were selected for comparison. IBI values and associated impairment status of sites varied from eight sites in three streams that were impaired, to six sites on the four reference streams which were acceptable. The highest diversity sites were the sites farthest downstream in three of the streams, where 6–19 species were collected per site. No fishes were collected in the lowest diversity site and no Pennsylvania species of concern were collected at any sites. Our results indicate that at least half of the stream fish assemblages in the Presque Isle Watershed are impaired, likely due to effects of urbanization.
Thirty-four species of molluscs have been found in the drainage systems of the United States Military Academy at West Point, NY. A few rare species were found as well as a single specimen of a presumed new gastropod taxon. Only two species of unionids, Pyganodon cataracta and Elliptio complanata, were found within the drainages. The largest drainage system, Popolopen Brook, contained the highest diversity of molluscs. Species redundancy between drainages aligned well as a function of the extent of lentic and lotic habitats with brooks and streams having a Bray-Curtis similarity index of ≈ 64.0 when compared to lakes and ponds. On the other hand, a number of species collected were found in only a single drainage. Total drainage area did not correspond well with diversity unless determined as total predicted usable habitat. Thus the drainages with the greatest number of discernible lakes, ponds, streams, and creeks, also had the highest molluscan diversity. On the whole, molluscan diversity of these drainages compared favorably to those of other regional New York sites, but relative abundance or population densities varied, with variations reflecting survey effort, time or season of collections, and incorporation of historic museum collections.
Spatial and temporal segregation of six coexisting species of Ophiogomphus (O. anomalus, O. aspersus, O carolus, O. howei, O. mainensis, and O. rupinsulensis) were studied in a 137.7 km reach of the Aroostook River in northern Maine. Collections of exuviae showed that O. mainensis was most abundant and dominated the assemblage at sites in the upper reaches of the study area and was in low numbers and percent of total Ophiogomphus at sites in the lower reaches of the study area. Ophiogomphus rupinsulensis was most abundant and dominated the assemblage at sites in the lower reaches of the study area but was absent or in low numbers and percent of total Ophiogomphus at sites in the upper reaches. Ophiogomphus anomalus and O. carolus were present at all sites and O. anomalus was generally more abundant and made up a higher percent of the total Ophiogomphus spp. than O. carolus. Ophiogomphus howei and O. aspersus were present at only a few sites in low abundance and percent of the total Ophiogomphus. Several species of Ophiogomphus coexisted as larvae in 0.20 m2 areas of the substrate.
There was little evidence of temporal segregation among the six species. All species had short seasonal emergence periods in June. Diel emergence was during the morning and early afternoon. Timing of seasonal and diel emergence either differed little or not at all among the six species. Species that we were able to identify in all larval stages (O. mainensis,O. anomalus, and O. howei) were present in a wide range of instars on all sampling dates (May to October) suggesting overlapping generations and multivoltine life histories. In all six species, some larvae remained in the final instar for almost a year before emerging as adults.
Invasive exotic plants have been identified as one of the major threats to ecosystem function and biodiversity. This study examined the distribution and abundance (cover and frequency) of invasive plants in natural habitats of the Quinebaug Highlands forest block (13,760 ha) of northern Connecticut and southern Massachusetts in relation to current and historical land use and site conditions. Multiple regression and GIS analyses were used to identify areas of high infestation and factors most useful in predicting invasions. Celastrus orbiculatus, Rosa multiflora, and Berberis thunbergii were the most frequent invasives. Past land use was the strongest predictor of invasive cover (r2 = 0.219) and richness (r2 = 0.303; p < 0.001 both regressions). Current land development and physical soil characteristics were also strongly correlated. These results add to our understanding of factors promoting plant invasions. Because invasive species control in natural areas is time- and resource-intensive, this information may enhance conservation efforts by increasing efficiency in predicting and managing biological invasions.
Effects of the non-indigenous shrub Rhamnus frangula L. (glossy buckthorn) on tree recruitment, herb cover, forest floor plant species richness, and R. frangula recruitment were tested in two southeastern New Hampshire Pinus forests using a randomized complete-block field experiment. The treatment, applied in January of 2000, was the presence of well-established R. frangula populations with three levels: R. frangula absent prior to experiment (“uninvaded”), > 90% R. frangula cover (“Rhamnus present”), and removal of > 90% R. frangula cover (“Rhamnus removed”). After 2 years of measurements, Rhamnus present had significantly lower first-year native tree seedling density than Rhamnus removed and uninvaded plots (0.11, 0.40, and 0.40 seedlings/m2 respectively). First-year native tree seedling density in the Rhamnus removed and uninvaded treatments were similar. Neither percent herb cover nor plant species richness were significantly affected by the removal of R. frangula in the two years following treatment. We believe these results indicate that the presence of dense R. frangula inhibits the establishment of tree seedlings. Rhamnus removed plots sampled one year after removal had five-fold greater first-year R. frangula seedling density than the other treatments. However, after two years first-year R. frangula seedling density was similarly low in all treatments (< 0.5 R. frangula seedlings/m2). Control efforts for R. frangula may need to focus on conspecific seedling emergence for at least two years following initial control.
Bear Oak (Quercus ilicifolia Wang.) presents a unique architecture in which there is a distinct outer set of leaves on the perimeter of the bush and another set of leaves on the inside. In this paper we examine the relationship between plant architecture, leaf-level physiology, and leaf damage patterns by insects. We measured net photosynthesis, stomatal conductance, and leaf water potential in response to different levels of herbivory or leaf-rolling in both outer- and inner-canopy leaves. Leaf-rolling occurred naturally and was mimicked by hand-rolling leaves to different degrees. Net photosynthesis, stomatal conductance, and leaf water potential varied depending upon a combination of leaf position in the crown and degree of rolling, but not herbivory. Outer-canopy leaves had significantly higher rates of net photosynthesis and stomatal conductance, but lower leaf water potentials and leaf areas than inner-canopy leaves. Leaf rolling had an effect upon photosynthesis and stomatal conductance, which varied depending on whether projected areas of rolled leaves or projected areas of the leaves after they had been unrolled were considered. In both canopy layers, using unrolled projected leaf areas, stomatal conductance and net photosynthesis decreased with increasing leaf rolling. In the outer canopy, using projected areas of rolled leaves, photosynthesis decreased while stomatal conductance increased with increasing leaf rolling. In the inner canopy, photosynthesis increased while stomatal conductance was unchanged with increasing leaf rolling. In all cases, leaf water potential increased with increasing leaf rolling. These results suggest (in order of likelihood) that either rolling creates an area of closed stomata (stomatal patchiness) proportional to the amount of rolling, or leaf specific hydraulic conductance increases, or stomata are responding to changes in the boundary layer of the leaf.
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