Grassy Habitats Research Articles

The efficiency of a new lightweight suction sampler for sampling aphids and their predators in arable land

SummaryA petrol driven machine, normally used to collect leaf litter, was modified to be used as a suction sampler for polyphagous predators in cereals and grassy habitats and aphids in cereals. Recovery efficiency of Araneae, Carabidae and Staphylinidae did not differ significantly between winter sampling from Agrostis stolonifera, Dactylis glomerata, Festuca rubra, Holcus lanatus or Lolium perenne although the structure of these grasses was very different. Summer sampling of aphids and their predators in winter wheat showed that the new sampler captured significantly more target organisms per unit area than did a traditional suction sampler. The machine was also lighter, cheaper and much easier to use than a traditional machine.

Red Imported Fire Ant (Hymenoptera: Formicidae) Infestation of Motorized Vehicles

Red imported fire ants (RIFA), Solenopsis invicta Buren, typically nest outdoors in open grassy or weedy habitats where their large, conical-shaped mounds are usually oriented toward maximum solar radiation. Although red imported fire ants are not considered to be an indoor pest, invasion of homes and other buildings does occasionally occur (Lyle & Fortune 1948, Green 1952, Bruce et al. 1978). Certain environmental conditions, such as favorable temperature, relative humidity and the presence of food and water, are necessary for the colony to survive indoors. Anecdotal evidence for infestation of tractor-trailers and other trucks also exists. We present here three case histories of RIFA invasion and successful colony establishment in motorized vehicles. In the first case, a 1987 Winnebago Chief 22 motor home owned by one of the authors (DJA) was found infested with RIFA on August 18, 1989. The vehicle was based near Bogalusa, LA where it had been operated for two months prior to discovery of the infestation. More than 500 workers were observed over a 5-day period. Apparently the colony was nesting in the insulation in the walls, however no queen or immatures were observed. Colony relocation within the camper, apparently in response to elevated temperature, was noted several days after the ants were first detected. The infestation was eliminated with several applications of aerosol synergized pyrethrins in combination with thermal smoke bombs. In case number 2, the owner of a 1987 Plymouth Sundance reported a possible RIFA infestation in his automobile to one of the junior author's (TCL) on May 10, 1991. A thorough inspection revealed that a colony of RIFA had established residence under the hood of the car. A considerable amount of organic matter, primarily leaf mulch, had accumulated in a depressed area about 17.5 cm wide running the length of the top of the firewall. The colony was located in this mulch. The queen was not detected, but > 100 workers and immatures were observed. Foraging workers were also seen within the passenger compartment. An interview with the owner of the automobile revealed that the vehicle was usually parked at his residence in Gulfport, MS, however this site had received a considerable amount of rain during the prior 7 days. The entire coastal area of Mississippi experienced an exceptionally wet spring in 1991 and the ground at that time was saturated with water. The ant colony may have been forced from it's original nest by the rising water, and sought refuge inside the automobile. Amdro? Fire Ant Bait was placed in a petri dish and set on the floorboard near the infestation. An inspection of the vehicle 72 hours post-treatment showed that no ants were present. The third case was noted on December 6, 1992. The senior author detected a RIFA infestation in the engine area of a personally-owned 1986 Buick Regal automobile. This vehicle had been operated in southern Mississippi for the six months preceding the detection of the infestation. Road trips of 60 miles during this interval were frequent, as were shorter trips of 5 miles or less. Two to three hundred workers (both minors and majors), larvae, pupae and the queen were found in the air pollution control canister. This cylindrical-shaped device (about 10 x 15 cm) provided an ideal nesting site because a built-in foam filter had become saturated with water which provided the necessary moisture. Soil particles, sand, and other road debris had been used to construct a nest

Seasonal Habitat Use and Abundance of Loggerhead Shrikes in South Carolina

Loss of winter habitat has been implicated in the widespread declines of loggerhead shrike (Lanius ludovicianus) populations; however, our understanding of what represents winter habitat for this species is poor. Thus, we investigated whether shrikes in South Carolina used similar habitats throughout the year. We found that during the breeding season shrikes inhabited areas dominated by short, grassy vegetation, whereas, outside of the breeding season, they decreased (P = 0.047) their use of grassy habitats and increased (P = 0.005) their use of cropland. Declines in shrike populations in the southeastern United States as well as the entire nation, respectively, were correlated (r = 0.83, n = 15, P < 0.001; r=0.34 n = 113, P < 0.001) with a loss of pastureland suggesting that this habitat may be limiting

Population dynamics of Arvicanthis niloticus (Rodentia: Muridae) in Kenya

The population dynamics of the Grass rat Arvicanthis niloticus were studied in relation to their diet and the climate in the Nakuru district of Kenya between September 1980 and May 1982. Numbers in the study area were low at the end of 1980 with groups of animals isolated in patches of grassy habitat. Local populations declined and some became extinct during the first half of 1981. Breeding began in April, one month after the start of the rains, but with a small initial population and high juvenile mortality, numbers did not increase significantly until September, when animals born earlier in the season were old enough to reproduce. This second generation reproduction was probably very important to the survival of the population over the following dry season when adult mortality was estimated at 15% per month.Reproduction was facilitated by a nutritious diet, consisting mainly of young grasses early in the season and seeds later on. Seed production was itself related to rainfall and as that declined towards the end of 1981, breeding ceased. Arvicanthis were considerably more numerous then than one year previously, with the difference being ascribed to the longer rainy season experienced in 1981 than 1980. The density of animals in favourable habitats increased with immigration from less suitable areas between January and March 1982, and then declined until the end of the study. Breeding resumed in April, one month after the start of the rains.Peak numbers of Arvicanthis were recorded in the middle of the dry season, when few crops were in the ground. They would only become a serious pest to agriculture if they were still abundant at the start of the breeding season some months later. Expansion then could result in very high numbers by harvest time, in August or September.

Three New Anemias from Northern South America

Of the over 100 species of Anemia, about 65 are found in southern and eastern Brazil with a secondary center of speciation in Mexico (20 species). Central America and the western and northern portions of South America have provided relatively few species, those being mostly very widespread taxa. Apparently this is a misleading picture since we here report three new species from northern South America-one from northern Brazil and two from essentially a single locality near Puerto Ayacucho in southern Venezuela. All three species are known from single collections and were found among granite rocks. It would seem that these areas have not been well collected, and since Anemia generally favors grassy and/or rocky habitats, there may be additional taxa yet to be discovered in southern Venezuela and Colombia and northern Brazil. pinnis fertilibus brevibus antrorsis falcatis et laminae pilis contortis discreta. (L., antrorsus, directed upward, referring to the habit of the fertile pinnae.) Rhizome horizontal, compact, ca. 6 mm diam., with brownish-yellow hairs, 5- 8 mm long; fronds erect, sterile and fertile fronds alike, 28-34 cm long; stipe slightly less than half the sterile frond length and slightly more than half the fertile frond length, densely hirsute with orange hairs 3-5 mm long; blade del- tate-ovate, 15-17 cm long, 8-10 cm broad, bipinnate-pinnatifid, lamina papyra- ceous, dull, pilose on both surfaces with multicellular hairs 0.5-1.0 mm long (twisted on abaxial surface), densely tomentose on rachillae, lower surfaces and rachis; sterile pinnae 9-12 pairs, subsessile (petiolules 1-2 mm), upper pinnae perpendicular to the rachis, lower pinnae slightly ascending, 5-7 pinnules per pinna, the lower pinnae slightly more exaggerated basiscopically, lobes acute to obtuse, margin entire to crenulate; veins free, evident; fertile pinnae remote from the sterile pinnae, ca. half as long as the adjacent sterile pinnae, ascending at 55? angle to strongly upwardly falcate, short-petiolulate (3-4 mm), the ultimate divisions with narrow laminar tissue; spores tetrahedral, vertically compressed, striate, the ridges broad with narrow grooves between, 69-79 (av. 76.1) ,tm diam. (Figs. 2A, B). This species bears a strong resemblance to A. tomentosa var. australis Mickel, but A. antrorsa is quite distinct with its short, suberect pinnae, strongly hairy stipe and rachis, and twisted abaxial laminar hairs. Such habit for fertile pinnae is otherwise well known in the genus, occurring in all three subgenera: subg.

Effect of Microhabitat Features on Habitat Use by Peromyscus leucopus

Habitat use and selection by the white-footed mouse (Peromyscus leucopus) were examined in riparian woods and associated grassy, shrubby and limestone outcrop habitats on the Konza Prairie Research Natural Area near Manhattan, Kansas. Analysis of captures on a large, irregular grid (843 stations) demonstrated significant differential use of habitat types by P. leucopus. Selection of habitat types was related to the vertical structure of the vegetation with areas of complex vertical structure (trees with large shrubs, large shrubs without trees or trees with small shrubs) selected over those with less well-developed vertical structure (trees without shrubs, small shrubs without trees or grass). The same basic pattern persisted when microhabitat features in the immediate area of traps were examined. Use of microhabitats associated with rocks, logs, stumps and fallen trees in the riparian woods revealed greater use of areas with dense cover. The use of microhabitats associated with limestone outcrops confirmed a pattern of greater use of protected than of open areas. Patterns of habitat and microhabitat use were generally consistent with the use of habitat features to avoid predators; however, food distribution was not examined and availability of food in different sites may explain part of the use patterns. Limited observations on habitat selection by Neotomafioridana suggested that competitive interactions between P. leucopus and N. floridana were relatively unimportant in the macroand microhabitat use patterns of P. leucopus.

Demography of the longtail vole Microtus longicaudus in seral stages of coastal coniferous forest, southeast Alaska

Microtus longicaudus is atypical of its genus as it most often occupies a shrubby rather than grassy habitat where it exists at low densities. Populations were monitored by biweekly livetrapping in three logged habitats and in an old-growth area during three reproductive seasons in order to investigate the relationship between habitat and demography. The most consistently high population densities were observed on a 7 to 10-year-old clear-cut. Densities were positively correlated with log and shrub cover within and between grids and with herb cover at a between-grid scale only. Habitat selectivity was higher at low densities. Densities declined on all grids during the 3rd year of the study; this resulted from poor overwinter survival on three grids and poor recruitment on one grid. Adult males survived poorly in relation to adult females during the breeding season and over winter. Consistently low overwinter survival and low growth rates of adults and juveniles on the 23 to 26-year-old clear-cut were associated with low nitrogen content of shrub species; dicot leaves constituted 30% of the adult diet. Fruit and seeds comprised 67% of the juvenile diet, and their phenology may be an important determinant of reproductive patterns.

How and Why Horses Open Crescentia alata Fruits

Costa Rican range horses break the hard, ripe fruits of Crescentia alata with their incisors and swallow the small seeds imbedded in the sugar-rich fruit pulp. The seeds survive the trip through the horse and germinate in large numbers where horses have defecated. The ripe fruits required about 200 kg pressure to break, and fruits that were too hard for the horses to break required 272 to 553 kg to break. Unbreakable fruits had thicker hulls, and their presence provides an example of how a fruit trait may serve to spread seeds among more than one kind of large dispersal agent. Crescentia alata (Bignoniaceae, 'jicaro') is a common and widespread shrubby tree in the lowland, grassy habitats o,f the Pacific side of Central America. It is native to this area, yet in many places the large, cauliflorous, hard, and indehiscent fruits (fig. la) fall to the ground below the tree, ripen over the next three-five weeks, and rot without ever being touched by a potential dispersal agent. The many small, soft seeds imbedded in the sugar-rich pulp die without germinating in the unopened fruits. This fate is typical even in National Parks containing an apparently normal fauna of large mammals. These observations bring to mind the question of what animal is the normal dispersal agent of C. alata and how does this agent eat such a large fruit? The answer is found in habitats where horses have access to C. alata trees. The brittle, ripe fruits are bitten open by range horses and the black, moist, sweet, and seed-rich contents are swallowed after only slight chewing. Many of the seeds survive the trip through the horse and shortly thereafter germinate in the remains o,f the dung (fig. le). The modern, introduced horse (Equus caballus) is a dispersal agent of C. alata, so, presumably, the Pleistocene horse that undoubtedly occupied C. alata habitats until 10,000 years ago was also (Janzen and Martin 1982). In Santa Rosa National Park, as elsewhere in the semi-forested pastures in the lowlands of Pacific coastal Costa Rica, range horses are avid consumers of the contents of ripe fruits of C. alata. Here I describe in detail how they do it, ask how much effort it requires, and consider the significance of the fruits that are so hard that horses cannot break them.

EVOLUTION OF HORNS IN UNGULATES: ECOLOGY AND PALEOECOLOGY

EVOLUTION OF HORNS IN UNGULATES: ECOLOGY AND PALEOECOLOGY

A New Species of Roscoea (Zingiberaceae) from Nepal

The British Museum expeditions of 1952 and 1954 to Nepal made 5 gatherings of a distinct new species of Roscoea which is not obviously allied to any of the other species known from this area. The collections are from 3 fairly widely separated areas in the states ofJumla, Piuthan and Palpa in northern central Nepal. The plants were flowering in June-July at altitudes between 2438 and 2743 m in open grassy and rocky habitats, as well as shady situations in open forest. The flower has unusual proportions for the genus. The dorsal petal is small and narrow, only I the length of the labellum; the orbicular staminodes are unusually large; the lateral petals are as long as the dorsal petal and completely hidden in growth by the very large labellum which has undulate margins and a V-shaped cleft for j-1 of its length. The labellum does not, as in most other species, narrow abruptly into a basal claw, and is held at a right-angle to the perianth tube as in R. purpurea Sm. (sensu stricto) and not hanging as in R. humeana Ballf. f. & W. W. Sm. and R. auriculata K. Sch. (R. purpurea sensu Hook. f.). Another unusual feature of this species is the very small appendages at the base of the anther. In most species the appendages are held at an angle to the thecae. In R. nepalensis they seem to lie in the same plane as the anther and are, in some examples, hardly noticeable. All collections have completely white flowers, and it would be interesting to see if more collections would uncover a purple form as happens in several species of this genus. All specimens cited have been seen.

Studies on the Autecology and Population Biology of the Weedy Monocarpic Perennial, Pastinaca Sativa

(1) Wild parsnip (Pastinaca sativa L.) is a monocarpic perennial herb which grows as a weed in North America in grassy habitats that are usually mown in summer. Flowering occurs in May and June, and seeds are mature by early July. Seeds remain attached to the dead erect shoots until autumn, unless the plants are disturbed, as by mowing. (2) At maturity small numbers of seeds can germinate at summer temperatures. As the seeds after-ripen during summer their ability to germinate at high temperatures increases, but there is little increase in ability to germinate at autumn temperatures. Stratification (moist chilling) over winter lowers the temperature requirement for germination, and therefore the majority of seeds in the field germinate in early spring. (3) Seedling mortality is high; of 3980 seedlings marked in a natural population in Kentucky, only thirty-three (0.83%4) flowered before dying. Cohorts of seedlings marked in August, November, December, January and April had concave survivorship curves; cohorts marked in February and March initially had concave survivorship curves, but the curves subsequently became linear. (4) Plants produce rosettes and grow until the second, third, fourth or fifth growing season before producing flowers. Vernalization is required for flowering, and plants reach the flowering stage quicker under long than under short days. (5) An old-field population showed a wide range of individual plant sizes in late May: flowering plants had root-crown diameters (RCDs) of 5-39 mm, and non-flowering plants had RCDs of < 1 (first-year seedlings) to 10 mm. It is suggested that plants must reach a critical size before they can respond to the environmental stimuli of vernalization and photoperiod.

Notes on habitat relationships of ungulates in Yankari Game Reserve, Nigeria

AbstractYankari Game Reserve in northeastern Nigeria consists largely of savanna woodland with trees on the better soils growing to 15 m and with spreading crowns. On shallow and stony soils the tree height is generally less and the canopy is discontinuous. The Gaji River riparian zone supports a wide variety of vegetation types ranging from evergreen, closed canopy forest to sedge meadows and patches of open grassland.Elephant (Loxodonta africana) range backwards and forwards along the riparian strip, feeding on perennial grasses and a variety of browse material and utilizing closed canopy forest patches for shade cover. The major movement patterns of other important herbivore species are perpendicular to the riparian strip. Areas used intensively are: waterbuck (Kobus defassa)–open savanna woodland immediately behind the riparian strip: Western hartebeest (Alcelaphus buselaphus major)– open grassy habitat in relatively poor woodland at middle distances from the river; Roan antelope (Hippotragus equinus)–patches of well‐developed and infrequently burned woodland, often at major distances from the river. Buffalo (Syncerus caffer brachyceros) during the dry season ranged between the riparian grassland areas and the more open sections of nearby savanna woodland, but travelled out to distant sections of the reserve after rainwater pools had formed.A major problem in management was the development of a burning policy that would maintain an appropriate balance between perennial and annual grasses and the shade providing trees.

Invasion of Florida by the "Lovebug" Plecia nearctica (Diptera: Bibionidae)

Plecia nearctica Hardy has spread eastward from Mississippi and Louisiana since 1940. Its range expanded approximately 32 km (20 miles) per year reaching southern Florida and South Carolina by 1975. P. americana Hardy, a native species, occurs in spring in woodland situations, whereas P. nearctica occurs throughout the year but most frequently in May and September and is most common in grassy habitats.

Functional Morphology of the Phallosome in Glossina (Diptera, Glossinidae) and Its Evolutionary Implications

Current views on the phylo-genetjc relations of the three species groups within the genus Glossina are critically reviewed. In respect of the male genitalia, the fusca group is here regarded as more specialized than the morsitans group. The detailed phallosome morphology of G. austeni is compared with that of G. fuscipes, on the basis of their mode of action in living flies. The comparison is extended to fusca group species, using dead material only. The presumed phylogeny of Glossina is presented in outline; the evolution of the genus has involved a progressive invasion of riverine and later of forest habitats, from an original semi-arid grassy woodland habitat.

Nesting Record of European Skylark in Washington State

The Skylark (Alauda arvensis) was introduced to Vancouver Island, British Columbia, Canada, in 1903 and 1913 (Carl and Guiget, British Columbia Provincial Museum Handbook 14, 1958). Bruce (Condor 63:418, 1961) gives a sight record for the species on San Juan Island, Washington, and Larrison (Washington Birds, Seattle Audubon Society, Seattle, 1968) includes it in an undocumented Rare and Accidental Species list. In 1969 Leslie Hall, a student at Western Washington State College, noted the species at the south end of San Juan Island. Further investigation showed several singing birds in an area of open, grassy habitat approximately one mile long and onethird mile wide. We searched the area, located at the monument marking the site of the American Camp during the Pig War of 1859-73, on 17 May 1970. After flushing an adult Skylark we found a nest containing three eggs, and we then followed food-carrying adults to a second nest containing four young birds a few days old. Both nests were within one-fourth mile of the monument. We estimated about 12 pairs of Skylarks in the area. Other species apparently nesting there included Savannah Sparrows (Passerculus sandwichensis) and Vesper Sparrows (Pooecetes gramineus). The area is heavily populated with European Rabbits (Oryctolagus cuniculus) and attracts numbers of eagles and hawks as well as foxes and other predators. Although the species may have introduced itself on San Juan Island years ago from Vancouver Island (about 15 miles away), as far as we can ascertain, this record is the first proof of its nesting in the state of Washington, and the only current record for the continental United States.

Population Ecology of Desert Rodent Communities: Habitats and Environmental Complexity

We investigated the relative densities of granivorous, nocturnal desert rodents in small plots within two arid regions of Arizona to study how sympatric species avoid competitive extinction. The most common rodents were kangaroo rats, Dipodomys spp., and pocket mice, Perognathus spp. We attempted correlating the density of each species with several environmental measurements, derived from the soil's i) depth; ii) texture or iii) resistance to sheer stress; or from the plant's i) species diversity; ii) growth forms or iii) foliage density. Successful variables were derived from plant growth form and foliage density. The soil's resistance to sheer stress also seemed important for a few species. In general, kangaroo rats were associated with sparseness of vegetation; pocket mice with denseness. One group of mice, which we term bush mice, seemed to require bushes and included two Perognathus spp., three Peromyscus spp., and probably a harvest mouse (Reithrodontomys fulvescens). Two other Perognathus spp. were taken in grassy habitats. Some suitable habitats tended to be complementary to others, suggesting that species associated with them are competitors. Comparisons of the density and distribution of D. merriami, present in both regions but under different biotic circumstances, reinforces the opinion that competition is responsible for the complementariness of habitats. In some cases the evidence suggests that competitive coexistence is accounted for by the fact that different specializations are needed to escape predation in different environments. We use variables which correlate with the relative density of various species to construct a model of habitat complexity. The rodent species diversities obtained in our plots can be approximately accounted for by this model. The model is based on the premises that the rodents collectively discriminate four qualities of soil surface, and three heights and two densities of vegetation. In general, specializations based on biotic variables appear most important.