Identify rabbits and their impacts
Large populations of rabbits are relatively easy to detect as the damage they cause is usually widespread and highly visible. However the damage caused by low density rabbit populations can be much harder to identify – and may be more serious (eg preventing regeneration of an endanagered plant species). Rabbit numbers, and changes in their impact, can vary dramatically in a short period of time. Without ongoing monitoring and control, these changes can go unnoticed and the problem can get out of hand, resulting in higher management costs.
Rabbit density is a practical indicator of a potential rabbit problem and can be measured easily, quickly and cheaply. Rabbit density can be estimated directly by counting rabbits or indirectly by counting warrens, active warren entrances or signs of rabbits (eg tracks, dung). Instructions on how to rapidly assess a rabbit problem using a simple, visual-based technique can be found in the booklet Rabbits: a threat to conservation and natural resource management. Detailed descriptions of other monitoring methods can be found in the books Monitoring techniques for vertebrate pests: rabbits and Managing vertebrate pests: rabbits.
Is it a rabbit, hare or bilby?
In some situations, it may be difficult to identify what animal you are dealing with, particularly if you are using indirect monitoring methods. There are animals of similar size and appearance to rabbits, such as hares and bilbies. Hares are an introduced species from the same genetic family as rabbits (Leporidae). They live in similar habitat types but are usually solitary, and do not build large warrens like rabbits. Greater bilbies are small, protected native animals that have similar sized tracks to rabbits, and also live in warrens.
Other key differences between the three species are:
- hares are noticeably larger than rabbits, with a head and body length of 55 cm while rabbits are about 40 cm in length
- a hare can weigh twice as much as a rabbit
- a hares hind legs are relatively larger than a rabbit’s
- hares can run faster than rabbits
- hares have relatively longer ears than rabbits, with distinct black tips
- rabbit warrens often have more entrances than bilby burrows, and entrances are usually larger
- rabbit diggings are generally shallower than bilby diggings, and tend to be long and narrow.
Measuring damage and costs
Simple damage assessments can also be used to identify a serious rabbit problem. These include visual assessment of crops eaten out 50 m from warrens, distinct ‘browse-lines’ 500 mm above the ground on shrubs and foliage within reach of the rabbits, increased presence and spread of invasive weeds, and scratching and soil disturbance. Quantifying rabbit impacts using other measures can be difficult, costly and time-consuming, and are generally not practical for many land managers. When assessing suspected rabbit damage to vegetation, crops or pastures, it is important to remember that other animals such as grasshoppers, hares and wallabies might cause similar damage.
PestSmart Factsheet RABFS3: Economic and environmental impacts of rabbits in Australia, Invasive Animals CRC (2012)
Guides to help develop a rabbit management plan:
- Victorian Rabbit Management Collaboration Initiative - Supports community-led action for more sustainable and effective rabbit management in Victoria
- Planning a strategic approach to pest animal management - Pest management plans should be based on the following steps
- Planning landscape-scale rabbit control - Covers important factors to consider in developing community-based rabbit control programs within the framework of natural resource management boards and their equivalents
- Glovebox Guide for Managing Rabbits - Current information on best practice rabbit management for land managers, pest animal officers and others involved in the management of rabbits
- Rabbits: a threat to conservation and natural resource management - Quick assessment method to help you decide if rabbits are a problem and what action you need to take