Suchergebnisse

The absolute and relative contribution to the finite rate of increase of
specific age classes was examined using projection matrix sensitivity and
elasticity analysis for a number of red fox
(Vulpes vulpes) populations. The fox populations that
were examined included urban foxes from England, rural foxes from North
America and rural foxes from Australia. The youngest age classes made the
greatest contribution to the finite rate of increase for all populations
studied. A pest management strategy that reduces survivorship and fertility of
juvenile and young adult foxes (Age Classes 1 and 2) will be the most
effective strategy for reducing a population's finite rate of increase.
The results indicate that fertility control may be as effective as lethal
methods for controlling some fox populations.

A review was conducted of literature relating to plagues of the house mouse in three agricultural regions of south-eastern Australia for the period 1900–70. Meteorological data, particularly in relation to rainfall, was surveyed during the same period. The two sets of data indicated that in each region plagues of the house mouse were preceded by drought conditions. The role of mouse predators and disease agents are discussed as possible explanations of this relationship.

The persistence of 1080 in two commonly used fox baits, Foxoff® and chicken wingettes, was assessed under different climatic and rainfall conditions in central-western New South Wales. The rate of 1080 degradation did not change significantly between the Central Tablelands and the relatively hotter and drier environment of the Western Slopes. Loss of 1080 from wingettes was independent of the rainfall and climate conditions, with wingettes remaining lethal to foxes for, on average, 0.9 weeks. Foxoff® baits remained lethal for longer than wingettes under all tested conditions, although their rate of degradation increased generally with increasing rainfall. As a result, areas baited with Foxoff® will require longer withholding periods for working dogs than those baited with wingettes, especially during dry periods. Wingettes may have advantages for use in sensitive areas where long-term hazards from toxic baits are undesirable. We found significant variations in 1080 concentration in freshly prepared baits that may result in efficacy, non-target and regulatory concerns for baiting campaigns. As a result, the superior quality control and shelf-stability of manufactured Foxoff® may be important criteria for favouring its use over freshly prepared bait types. However, use strategies for any bait type must ensure that foxes consume lethal doses of 1080 to avoid potential problems such as the development of learned aversion to baits or pesticide resistance.