The method is simply counting the rabbits, which emerge from a warren at a specific time for example, 2 hours before dusk. An observer watches and counts the numbers of adult, sub-adult and juvenile rabbits that appear on a warren or a number of warrens over a fixed time period.
This is done from an elevated and concealed observation position. The number of warrens chosen depends on the availability and the number of observers. Generally, only rabbits on one or two warrens can be counted during the peak activity period.
Note:- this method may not give reliable estimates of the number of very young rabbits in a warren.
Young rabbits emerge from the burrow from 21 days of age. Young rabbits behave more timidly than adults and may be harder to observe. Counts need to be on a monthly basis because pregnant does can drop a new litter of rabbits every month. Sub-adults generally disperse from the warren at 1-2 months of age.
Choosing a warren:
A warren should be chosen based on the following criteria:
- select warrens that are representative of the land type/land class
- rabbits can exhibit normal behaviour and activities with no effect from the observer
- differentiation between adults, sub-adults and kittens is possible
- 2 or more warrens can be observed
- any rabbit control (poisoning, fumigating, ferreting, shooting ) in the area of the monitored warrens can be noted
- warrens where no rabbit control is planned can be included in the monitor program
When to count?
Counting of the rabbits on a warren needs to coincide with the peak activity of the warren. This is when most rabbits are moving out of the warren for a feed. The peak in activity is likely to be 2 hours before sunset. If vegetation is short the greatest number of rabbits is usually seen in the last hour before dark.
To determine this, observations are required over a couple of days during the mid afternoon to dusk period. The peak activity should occur approximately the same time before dusk each day, so long as there has been “normal” seasonal weather conditions and no disturbance of the warren.
Setting up a warren/rabbit count site:
- name the warren site
- record warren site on map
- record the dimension of the warren count area
- GPS warren site
- be able to observe 2 or more warrens
- ensure access to observation point does not disturb rabbits or wait until rabbits have settled
- observations of rabbit behaviour can be made
- easily visible: warren surface (including entrances) and surrounding area are visible
- check that the warren boundary is clearly identifiable from the observation site
How to count?
- count at the determined peak activity time
- every 15 minutes count the number of rabbits on the warren
- peak activity is when most rabbits are counted per period.
or
- observe the warren at the same time before dusk without determining peak activity for approximately 45 minutes (ie. 2 hours before dusk) and for both methods
- standard data sheets can be obtained from NRE offices
- record the weather conditions (temperature, wind direction/speed, precipitation)
- record time, date, observers present, name of counter and recorder
- do two, three or more counts consecutively, note variations
- each month do a warren/rabbit count
Remember: - use the same method for the same warren systems and note if changes to the counting method are being used. Combine this method with spotlight and active entrance counts for a more accurate assessment of rabbit populations. Binoculars can be used to improve visibility (use same magnification & field of view, each time).
What to count?
- number of juveniles, sub-adults and adults
- predator presence
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