Suchergebnisse

The diet of the allied rock-wallaby, Petrogale assimilis, an inhabitant of the wet-dry tropics of North
Queensland, was studied over three years by microscopic faecal analysis, feeding observations, and an
analysis of the ratios of the natural isotopes of 12*C and 13*C in the faeces. Forbs were the major food
item, accounting for 22-65% of the identified epidermis in the faeces, and tended to be actively
selected by the wallabies. Browse (20-41%) and plants with stellate trichomes (6-32%) were the next
most-important dietary items, the latter being eaten in significantly higher proportions in the dry seasons
of 1987 and 1988. Grass comprised only 5-16% of recognisable epidermis in the faeces, but was eaten
in significantly higher proportions when fresh new growth was available. Forbs were difficult to identify
at night, and most plants that rock-wallabies were recorded eating were those with stellate trichomes
rather than forbs. The low incidence of grass in the diet was confirmed by the carbon-ratio analysis.

AbstractSince the days of Mayor Hylan politics has dominated the filling of the higher posts in New York Ciiy's public schools. Persistent efforts at reform have been frustrated.

AbstractMore than 2,000 provisional appointments are being continued in violation of law. Is it proper or just to blame the civil service commission?

Abstract"When we see a lot of framed timbers, different portions of which we know to have been gotten out at different times and places by different workmen, Stephen, Franklin, Rogre and James, for instance, and we see all these timbers joined together and see that they exactly make the frame of a house … we find it impossible not to believe that Stephen and Franklin and Roger and James all understood one another from the beginning."—Abraham Lincoln.

AbstractThe secretary of the Civil Service Reform League takes issue with Mr. Fosdick, author of American Police Systems, regarding the place of civil service examinations in police administration.

The teeth of rock-wallabies from a wild population of Petrogale assimilis at 'Black Rock' in north
Queensland were radiographed in the field at intervals over two years in order to estimate their age. The
gross morphology of the dentition conesponds with that of browsing macropodids. The pattern of tooth
eruption conforms to the general macropodid model. Although P. assimilis reach sexual maturity at 18-24
months, full molar eruption apparently does not occur until individuals are at least seven years old. The
plane of the occlusal surface is only slightly curved. Most of the cheek teeth are in occlusion at once. In all,
70% of wallabies examined at 'Black Rock' had a full complement of cheek teeth. P4 is well developed and
rarely lost. These attributes collectively suggest that the small amount of mesial movement of the molars
constitutes advanced mesial drift rather than true molar progression. Molar eruption is a reliable index of
age until full eruption occurs. Molar movement is likely to be of only limited use in estimating the age of
animals with a full complement of cheek teeth. The age structure of the colony at 'Black Rock' suggests a
low rate of recruitment into the adult population of P. assirnilis for most of the 1980s.

In 1984 and 1985, during surveys designed primarily to census dugongs, six species of sea turtles were counted
from the air at an overall sampling intensity of 9% over a total area of 31 288 km2 within the northern sections
of the Great Barrier Reef Marine Park. The sea turtles were not identified to species. We attempted to correct
sightings for perception bias (the proportion of animals visible in the transect which are missed by observers),
and to standardise for availability bias (the.proportion of animals that are invisible due to water turbidity)
with survey-specific correction factors. The resultant minimum population estimate in November 1985 was
(mean � s.e.) 32 187 � 2532 sea turtles at an overall density of 1.03 � 0.08 km-2, a precision of 8%. We
consider this to be a gross underestimate of numbers present. Significant differences between population and
density estimates obtained from repeat surveys of the same areas were accounted for by differences in
Beaufort sea state and cloud cover. The analysis of covariance data suggested that we had not been successful
in standardising all biases. Turtles were widely distributed throughout the Great Barrier Reef lagoon from
inshore seagrass beds to mid- and outer-shelf reefs. Highest densities were observed on inshore seagrass beds
and on mid-shelf reefs, particularly between Murdoch Island and Cape Melville, and in Princess Charlotte
Bay. Maps of density and distribution are given. We discuss the value and limitations of this survey regime for
censusing sea turtles.

Some factors which affect the aerial counts of dugongs and sea turtles were examined experimentally.
There was no significant difference in the observed density of dugongs when survey height was doubled
from 137 m to 274 m with an accompanying doubling of transect width on either side of the aircraft
from 200 m to 400 m. In contrast, a significantly higher density of turtles was observed at the lower
heightharrower transect width. The higher level of glare on the exposed side of the aircraft, the time
of day and the time from high tide made no significant difference to the observed densities of dugongs
or turtles. The survey crew included a tandem team of two observers on each side of the aircraft,
who reported their uncolluded observations into separate tracks of a two-track tape recording system.
This allowed the reports of tandem observers to be compared in order to assess observer reliability.
Overall, observers missed over 40% of dugong groups and over 80% of turtles visible within the
transect including groups of more than 10 dugongs. The chance of observers missing a group of
dugongs was independent of group size. There was little disagreement between tandem observers about
the identification of animals, or the position of animals in the water column. However, observers
differed markedly in their categorisation of dugong behaviour and in their counts of animals
(particularly dugong calves) in larger groups.