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Geology topics

Charles van Riper

Publications and source records attributed to Charles van Riper.

At least 109 records · Page 6Linked to original sources
USGS1990

Comparative susceptibility of Culex tarsalis, a Nopheles franciscanus, and Culiseta inornata (Diptera: Culicidae) to Plasmodium relictum (Haemosporidia: Plasmodiidae)

Repeated laboratory attempts failed to infect Culiseta inornata (Williston) and Anopheles franciscanus McCracken with Plasmodium relictum as efficiently as Culex tarsalis Coquillett controls. Of 210 An. franciscanus that imbibed a replete meal from a parasitemic canary, two were found with oocysts and none with sporozoites. Of 112 Cs. inornata similarly fed, seven contained oocysts and one contained sporozoites. In contrast, of 94 Cx. tarsalis tested, 80 (85%) were found with oocysts, thus confirming that this mosquito is a suitable host of P. relictum . Lack of An. franciscanus and Cs. inornata with sporozoites precluded transmission studies and indicated that these species do not play a major role in the maintenance of P. relictum during fall and winter in the Sacramento Valley, Calif.

Journal of Medical Entomology↗
USGS1990

Water-vapor pressure in nests of the San Miguel Island Song Sparrow

The water-vapor pressure (P N ) in nests of the San Miguel Island race of Song Sparrows ( Melospiza melodia micronyx ) averaged 16 torr, but varied considerable between nests and within individual nests during successive days of incubation. Large daily fluctuations occurred throughout the incubation period and did not parallel concurrent changes in ambien vapor pressure (P 1 ). Daily rates of water loss from nest eggs (M H 2 O ) averaged 28 mg day -1 , but also varied considerable within and between nests and did not correlate with changes in P 1 . M H 2 O increased 6-33% after the third day of incubation. P N was significantly higher and M H 2 O significantly lower in nests located in sheltered gullies than in nests from a windswept slope. These data suggest that Song Sparrows do not regulate P N to achieve hatching success.

California↗
USGS1990

Evaluation of wildlife-habitat relationships data base for predicting bird community composition in central California chaparral and blue oak woodlands

The California Wildlife-Habitat Relationships (WHR) database can be used to assist resource managers to evaluate effects of habitat manipulations on wildlife. The accuracy of predictions from WHR was evaluated using data from bird surveys conducted during winter and spring 1984 and 1985 in chamise ( Adenostema fasciculata ) chaparral, mixed chaparral and blue oak ( Quercus douglasii ) woodland. Considerable variability between habitat types was found for errors both of commission and of omission.

California↗
USGS1984

Annual variation in the distribution, abundance, and habitat response of the palila ( Loxioides bailleui )

We studied the distribution, population size, and habitat response of the Palila ( Loxioides bailleui ) during the 1980-1984 nonbreeding seasons to infer factors that limit the population and to develop management strategies. Distribution was fairly constant from year to year. Palila were confined to the subalpine woodland on Mauna Kea on the island of Hawaii, occurred between 2,000 and 2,850 m elevation, and reached highest densities on the southwest slopes. The population showed large annual fluctuations, from 6,400 birds in 1981 to 2,000 in 1984. The width of woodland was the most important variable in determining habitat response. Palila were more common in areas with greater crown cover, taller trees, and a higher proportion of native plants in the understory. Annual variation in Palila density within a habitat reflected variation in levels of their staple food, mamane pods. The main limiting factors of the population appeared to be the availability of good habitat and levels of their staple food. Palila had strongly depressed densities in the Pohakuloa flats area. This low density could not be explained by gross habitat features or food levels. Site tenacity, thermal stress, disturbance, and disease were hypothesized explanations. Our study indicated that the most effective management strategies would be the removal of feral ungulates and certain noxious plants from Palila habitat and the extension of the woodland zone to areas now intensively grazed.

The Auk↗
USGS1980

A necropsy procedure for sampling disease in wild birds

This paper presents a necropsy procedure for examining small wild birds, designed to be used by investigators without experience in avian pathology. It gives instructions on how to conduct a postmortem examination, lists the needed equipment, tells what parts of a bird to save when a disorder in encountered, and lists possible diseases which each may signify. This procedure would enable ornithologists to include parasites and diseases in their investigations of avian populations.

Condor↗