Reproduction in Hypsiglena

A clutch of 8 eggs was incubated. Three hatchlings emerged and were weighed, measured and color pattern indicated.     

Male size and territoriality in the cicada killer wasp Sphecius speciosus (Hymenoptera: Crabronidae)

Males of the eastern cicada killer wasp, Sphecius speciosus, occupy territories in which they may hover or where they may perch either in trees near one or more emergence holes or on the ground at these spots from which females may emerge. Large males are more likely to hold and defend these territories at a site in northern Virginia. When resident males were captured, held and weighed, the males that replaced them, which were also captured, held and weighed, had significantly lower body weights on average than the residents.     

Patterns of energy allocation within foragers of Formica planipilis and Pogonomyrmex salinus

Foraging workers of Formica planipilis and Pogonomyrmex salinus were collected at various distances from their colony by pitfall traps in the former species and by catching workers recruited to food at known locations in the latter. In F. planipilis the number of larger workers increased in proportional representation to distance from the nest. Larger workers also weighed relatively less with distance from the nest, indicating that energy or water allocated for maintaining all foragers is patterned such that resource loss with forager mortality is minimized. However, the smallest size class involved in foraging shows the opposite pattern, with heavier individuals being found farther from the nest. Thus, it is possible that smaller size classes function as mobile reserves of energy or water to maintain foraging activity of larger classes at a distance from the colony. In P. salinus all sizes of workers were equally likely to be found at any distance. Foragers weighed significantly less than mound workers of the same head size, again suggesting resource conservation in provisioning foraging workers. Differences in patterns of energy allocation to foragers are discussed relative to the species' ecologies.     

Breeding in the gray-headed tody-flycatcher (Aves: Tyrannidae) with comments on geographical variation in reproductive traits within the genus Todirostrum

The gray-headed tody-flycatcher Todirostrum poliocephalum is a passerine endemic to the Atlantic Forest of Brazil. We describe the nest and nesting behaviour of this species and investigate geographical variation in breeding traits in the genus using data from the literature, museum collections, and citizen science projects. We located 21 nests of the gray-headed tody-flycatcher, 13 of which we monitored. Nest height above the ground averaged 3.3 ± 3.4 m (n = 21). Nests were built over a 16.8 ± 5.6-day period (n = 6) by both adults. Clutch sizes ranged from two to three eggs, with a mean of 2.9 ± 0.3 eggs (n = 10). Eggs measured 16.6 ± 0.5 × 12.0 ± 0.5 mm (n = 23) and weighed 1.1 ± 0.1 g (n = 19). Mean incubation period was 17 days (n = 3) and mean nestling period was 15.5 days (n = 2). Apparent reproductive success was 30.8%, with predation being the primary cause of nest failure (46.1%). Mayfield’s reproductive success was 25.9%, and daily survival rates for eggs and nestlings were 0.957 and 0.971, respectively. Clutch sizes increased with latitude, but temperature and precipitation seasonality had very low importance in explaining clutch size variation.     

Rodent populations, biomass, and community relationships in Artemisia tridentata, Rush Valley, Utah

Three desert Artemisia tridentata communities in Rush Valley, Utah, were trapped for small rodents during the summer of 1970, and population densities were estimated for each population category using Lincoln's index. Animals were weighed and rodent biomass calculated by species throughout the summer. Population, biomass, and other data were then analyzed to gain an understanding of the community relationships of the three study areas to each other as well as to the A. tridentata community types of the Great Basin. Peromyscus maniculatus, Eutamias minimus, and Reithrodontomys megalotis were common to area 1, whereas P. maniculatus, E. minimus, and Perognathus parvus were common to areas 2 and 3. The peak estimated standing crops were 182.8 (74.0). 143.1 (57.9), and 129.7 g/acre (52.5 g/ha) for areas 2, 1, and 3 respectively. The population and biomass of area 2 peaked in midsummer, area 1 early summer, and area 3 late summer.     

Interspecific differences in grass seed imbibition

Seeds from 12 grass species were studied relative to mode of wetting and time of exposure to water to document interspecific differences in imbibition characteristics. Imbibition causes seeds to become wet, and wet seeds are more detectable to consumers than dry seeds. Thus, germination potential and ability to remain undetected by consumers may represent an important trade-off. Seeds wetted for 0-192 h in vials imbibed water at rates equivalent to seeds wetted by contact with wet paper towels pressing against their seed coat, except for seeds of Avena sativa , which weighed more after wetting in 2-mL vials with free water (0.471 g vs. 0.432 g). Seeds from different species imbibed water at different rates. These data show that interspecific variation in imbibition for seeds is high and support an expectation that imbibition potential can interact with detectability to consumers in an evolutionary trade-off.     

Larval growth rates and sexual differences of resource allocation in the cetoniine scarab Mecynorhina polyphemus Fabricius 1781 (Coleoptera: Scarabaeidae: Goliathini)

Larval ontogeny of the scarab Mecynorhina polyphemus was monitored throughout all instars, and larvae were weighed at 7-day intervals. Durations of the prepupal, pupal and postpupal stages were recorded. Larvae increase their body masses over 300 times during ontogeny. Male imagines are larger than females, and this is primarily a function of faster growth rates during instar III, resulting in significantly heavier larvae at the end of this instar. The durations of the three instars are not significantly different in males and females, but the duration of the prepupal and postpupal phases is significantly longer in males. There is a strong correlation in both sexes between maximal larval mass and the mass of the imago, but larval mass–imago mass scales with significantly different slopes in males and females. Male larvae must allocate increasingly more resources into production of cephalic horns with increments in larval mass, requiring differently proportioned pupal chambers.     

Body size, body composition, and behavior of juvenile Belding ground squirrels

Juvenile Belding ground squirrels were studied in the Sierra Nevada. Females were more trappable, had smaller home ranges, and tended to enter hibernation earlier than males. The primary sex ratio was 1:1. Individuals first emerged from the natal burrow at three to four weeks of age and a body weight of 35 g. Body weight and linear dimensions increased thereafter until hibernation began. Maximum prehibernatory weight of 200 to 260 g was attained at about 12 weeks of age. Prehibernatory fattening began at about six weeks of age. Maximum lipid stores attained weighed about 80 percent of the lean, dry body compartment. Seasonal changes occurred in weight of white and brown fat depots, adrenal glands, spleen, heart, kidneys, liver, and testes. Annual variations in snowpack and emergence schedule caused the reproductive period, and thus phenology of juveniles, to vary by as much as three weeks. The last animals to immerge were unusually small, being from late litters. Nonetheless, they may have had lipid stores sufficient for surviving hibernation.     

Needle biomass equations for singleleaf pinyon on the Virginia Range, Nevada

Foliar biomass of singleleaf pinyon ( Pinus monophylla Torr. & Frem.) was estimated on the Virginia Mountains, Nevada, based on the easily measured dimensions of crown volume and sapwood area. Leaf biomass estimation techniques used in other studies of pinyon where total leaf biomass was collected were supported. Both sapwood area (cm 2 ) and crown volume, calculated as one-half of an ellipsoid (m 3 ), were found to be significantly related to total dry weight needle mass (g). Best predictive equations for crown volume were obtained with nonlinear regression analysis. A previously reported two-part relationship based on tree size for predicting needle biomass with sapwood area was supported. Foliar biomass of singleleaf pinyon can be accurately estimated with a minimum of 10 sapwood cores.     

Demographic characteristics of American marten populations in Jackson Hole, Wyoming

Some American marten population characteristics (numbers, density, body weights, sex and age ratios, natality, mortality-survivorship, immigration-emigration, home ranges) were studied at four sites in the southern part of the Greater Yellowstone Ecosystem, Teton County, Wyoming, in 1975-1979. Ninety-eight different martens were examined. Males (n = 25) weighed 1,111 g (± 110 SD, range 875-1,235), whereas females (n = 17) averaged 743 g (± 83 SD, range 600-900). Live-trapping showed sex ratios of 1.5M:1.0F, whereas carcasses showed 3.0M:1.0F. Of 27males that were aged, 12 (44%) were less than 1 year old and 2 were 9-10 years old. Of 10 females, 6 were less than 1 year old and 1 was 12-13 years old. The mean length of time a male was present on the major study area was 144 days (± 266 SD, range 1-1,364), and for females it was 145 days (± 45 SD, range 1-560). Home ranges for six males averaged 3.2 km 2 (± 20 SD, range 0.7-5.8) on the main study area. Some management implications are given.     

Growth of Plecoptera (stonefly) nymphs at constant, abnormally high temperatures

Six species of Plecoptera were maintained at four different temperatures, which were constant and higher than occurred in the natural habitat, and three species at two different day lengths. Each animal was weighed each day or each week. Weight of two species in the wild was monitored from periodic collection. The weight of each animal fluctuated rhythmically, changing about five percent every five days. These short - term fluctuations probably resulted from changes in water content. Molting occurred when a peak weight was predicted from the cycle and involved temporary gain of about 20 percent in weight. Growth probably stopped for some time before molt and was most rapid just afterward. Many animals died at molt. The time before death was less for univoltine species than for those with longer life cycles. Plecoptera collected in winter from water near 0 C lived for shorter times than did those collected in autumn from water near 10 C. Two species died sooner at higher temperatures and one died sooner with shorter day lengths. Growth in the laboratory was generally slower than in nature. One species grew faster, while three grew more slowly at higher temperatures. One species grew faster under long - than short - day conditions. Premature emergence, expected at the higher temperatures, did not occur, except in one animal.     

Breeding biology of the Double-crested Cormorant on Utah Lake

Research on the nesting of the Double - crested Cormorant ( Phalacrocorax auritus auritus ) was undertaken to determine the breeding biology of the bird on Utah Lake, Utah County, and the possible effects that diking Provo Bay would have on the cormorants breeding there. In 1973, two colonies in Provo Bay were visited weekly to determine laying dates, incubation period, clutch size, and hatching dates. Another colony, located on the dike of the Geneva Steel Works Reservoir near Orem, was visited daily during the spring and summer of 1973. At this colony egg-laying occurred from 13 April to 17 May. The average clutch size was 3.8, and the egg length and width averaged 60.50 mm x 39.05 mm. The average period of incubation was 28 days, and 29.5 percent of the eggs hatched, beginning on 20 May and ending on 9 June. The young weighed an average of 36 gm at hatching with a beak length of 17 mm and tarsometatarsal length of 11 mm. These measurements increased to 1543 gm, 73 mm, and 58 mm, respectively, in 23 days. The cormorant population on Utah Lake may be severely reduced by the proposed diking of Provo Bay.     

Resident Utah deer hunters' preferences for management options

A total of 3291 resident deer hunters returned questionnaires distributed at checking stations in fall 1989 and 1990 providing opinions and management data concerning the Utah rifle hunt. Hunters reported hunter crowding and too few big bucks as critical reasons for possibly choosing to quit deer hunting in Utah. Indeed, hunter age structure and measured satisfaction suggested a negative future trend in hunter participation. Results suggested the adoption of several hunter-preferred management options would increase satisfaction, motivation, and success.     

Present effects of past wildfires on leaf litter breakdown in stream ecosystems

We investigated the present effects from a 10-year-old wildfire on leaf litter breakdown rates in 3 headwater streams in central Idaho. These systems experienced a massive debris flow one year after the fire. Based on soil instability and burn patterns, we identified 3 stream conditions: unburned, burned only, and burned/scoured. We placed leaf bags containing willow leaves ( Salix sp.) in each stream type and removed bags at various time intervals until all bags were collected 100 days after their introduction. Leaf material was dried and weighed, and decay rate coefficients were calculated. Macroinvertebrates colonizing the bags were enumerated and identified, and selected taxa were placed into trophic groups. We found that the unburned stream had the fastest leaf litter breakdown rate, the lowest level of incident light reaching the stream, and the largest amount of benthic organic matter. The burned/scoured stream was nearly opposite in all respects. Numbers of 2 detritivore invertebrate taxa, Serratella tibialis and Zapada oregonensis, were highest in the unburned stream but lowest in the burned/scoured stream. A third taxon, Baetis sp., showed the opposite relationship. Presence of predatory invertebrates did not affect detritivore abundance or leaf decay rate in the bags. Our research suggests that recovery response variables of some stream systems may not have returned to prefire levels even a decade after the initial wildfire. In this study, the recovery of our streams appears to be connected to the return of the riparian zone, though fire-induced debris flows may slow or alter final recovery of the stream system.     

Caddisfly (Trichoptera) assemblages along major river drainages in Arizona

Seventy-two caddisfly species in 36 genera and 15 families were collected along the Little Colorado, Verde, Gila, and Colorado rivers in Arizona. Brachycentrids, hydropsychids, limnephilids, and uenoids made up nearly 50% of the assemblage in forested sites above 2200 m. Hydropsychids, hydroptilids, and leptocerids made up 75% of the assemblage in grassland watersheds between 2200 and 1000 m, and 80% at sites below 1000 m in desert watersheds. Species richness averaged 16 at sites above 2200 m elevation, 7 between 2200 and 1000 m, and 3 below 1000 m. H' diversity was typically >3 at sites above 2200 m and <2.5 below 2200 m. Each river had distinct faunas likely due to isolation of drainages across semiarid landscapes. Low S&oslash;rensen similarity values were measured for caddisfly assemblages in the highly regulated Colorado River and the other 3 rivers. Only 17 species were collected at 14 sites along 700 km of the Colorado River. Indicator caddisfly species are provided for altered and less disturbed drainages. We added 7 species not previously reported in Arizona for a total of 154 caddisfly species in the state. We provide a baseline of caddisfly indicators for monitoring changes in ecosystem health during the predicted long-term drought and population expansion in southwestern USA.     

Lakeward and downstream movements of age-0 arctic grayling ( Thymallus arcticus ) originating between a lake and a waterfall

Arctic grayling in Deer Lake, Montana spawn only in the 350-m segment of outlet stream between the lake and a waterfall. The purpose of this study was to examine consequences of and possible adaptations by this population to spawning above the falls, by determining the extent of loss over the falls of age-0 young, the daily and seasonal patterns of such losses, and the seasonal pattern of movement upstream into the lake by the remaining young. We measured fish movements during 1989 and 1990 with traps placed at the outlet and at the falls, from fry swimup in July until October or November. Young went over the falls predominantly as newly swimming fry at night. In 1989 about 5000-9000 were lost downstream, representing an estimated 4-7% or less of young produced. Most young thus appear adapted to maintaining their position above the falls. A few started entering the lake in August and September, but only 95 in 1989 and 23 in 1990 had done so by the time observations were ended by the onset of wintery conditions. Most movement into the lake appeared to occur sometime during the six to seven months of annual ice cover. This extended period of stream residence contrasts with early lakeward movements reported for other inlet-spawning, lacustrine grayling populations and may be an adaptation for avoiding predation by large conspecifics in Deer Lake.     

The freshwater crustaceans (Cladocera: Copepoda) of Bering Island (Commander Islands,Russian Far East): species richness and taxocene structure

The crustaceans of the fresh waters of Bering Island and their link to the fauna of adjacent regions were studied. Based on original data and existing literature, the species composition of Cladocera and Copepoda was described. The compiled list includes 22 species of Cladocera and 30 species of Copepoda. In the original data, 35 species native to the Commander Islands were reported for the first time. Six species were newly reported in the Far East, and two were newly reported in Russia. The ecological peculiarities of several species and some biogeographical features of the freshwater zooplankton of the island are discussed. The main part of the fauna of the island form Holarctic widespread species (64.3%), another slightly smaller group of the fauna is comprised of Palaearctic species (20.1%), and the remainder comprise Nearctic (6.7%) and Beringian species (8.9%). Particular patterns in the distribution of freshwater zooplankton and the factors underlying the occurrence of these species on the island are considered.     

Herpetological notes from the Nevada Test Site

During the years 1965 &ndash; 1971, considerable data were gathered that included information concerning species not previously reported. These included Chionactis occipatalis talpina, Coleonyx variegatus utahensis, Crotaphytus collaris bicinctores, Cnemidophorus tigris tigris, and Sauromalus obesus obesus. Although complete information concerning their life histories is not reported, some information concerning growth and reproduction is included.     

Phlox longifolia Nutt. (Polemoniaceae) complex of North America

Over 1,000 herbarium specimens including 24 type specimens were examined in an attempt to achieve a clearer understanding of the Phlox longifolia complex. Four variables were measured for each specimen and the data were statistically analyzed by discriminant analysis. Using a previously published system of classification for the complex, approximately 73 percent of the measured variation among the specimens was accounted for by that system. The clustering patterns produced in this first analysis indicated that a more conservative approach would be advisable. The formulation and subsequent application of a modified system produced a grouping of specimens that accounted for 95 percent of the measured variation for the four morphological characters considered. From four species and seven subspecies previously recognized, one species with five varieties is proposed. The typification of Phlox longifolia Nutt. and other related taxa is resolved. &nbsp;&nbsp;     

The scotopic visual sensitivity of four species of trout: a comparative study

We compared the maximum scotopic visual sensitivity of 4 species of trout from twilight (mesotopic) to fully dark-adapted vision. Scotopic vision is the minimum number of photons to which a fully dark-adapted animal will show a behavioral response. A comparison of visual sensitivity under controlled laboratory conditions showed that brown trout ( Salmo trutta ) and brook trout ( Salvelinus fontinalis ) had maximum scotopic thresholds (1.1 × 10 –4 μmol ? m –2 s –1 , ～0.005 lux) 2 times lower than rainbow trout ( Oncorhyncus mykiss ) and Snake River cutthroat trout ( Oncorhynchus clarki bouvieri ), which did not differ from each other (2.1 × 10 –4 μmol ? m –2 s –1 , ～0.01 lux). A literature review tended to corroborate these results in that brown trout and brook trout were reported to be more active during the night and at twilight than cutthroat trout and rainbow trout. We also measured light intensity within open versus shaded reaches during the day, dusk, and night in 3 Rocky Mountain streams. The scotopic sensitivity of brown trout and brook trout was sufficient to allow foraging during all twilight periods and under average nighttime light intensities in open and shaded reaches, whereas the scotopic sensitivity of rainbow trout and cutthroat trout may restrict their foraging to relatively bright nocturnal conditions (twilight or a moonlit night). Native cutthroat trout restoration efforts may have greater success in open versus shaded stream reaches in the Rocky Mountains and elsewhere.