Landcare Agony Aunt – Rabbits: the Return

Dear Agony Aunt,

We have had problems with rabbits on our property in the past but since 2020 the numbers have declined. Recently we noticed some scratchings towards the creek that seem fresh. Could it be rabbits back again? We don’t want to plant up our riparian zone yet, if that is the case. If they are back, what do we do next?

from Vexed in Vacy

Dear reader,

Thanks for reaching out about this problem.  As Landcarers we deal a lot with weeds, regeneration and replantings, but it is important to look at the broader ecological picture of your site and how animals are hindering or helping your efforts. 

According to Sharp and Saunders (2012):

“After the breaking of a drought, rabbit populations are held at low densities for several years by a combination of native predators, foxes and feral cats.  It is not until fox and feral cat numbers decline some time after the crash of the rabbit population, and good seasons return, that rabbit numbers build up again.” 

It sounds like this may be happening on your property. There were also some releases of biological control agents that aimed to control rabbits in the early 2020s which may have contributed to your reduced sightings of rabbits. 

As you probably know, European rabbits (Oryctolagus cuniculus) compete with native wildlife for food and shelter.  They spend 2.5-6 hours per night grazing on native vegetation and can prevent ground flora, vines and understory plants regenerating by eating roots and new growth and ring-barking saplings.

Rabbits are also linked to increases in toxic weeds in pasture, and unpalatable woody weeds in open woodlands.  They generally graze plants down to 4cm or less in height.  If there’s no water source available, rabbits are able to derive sufficient moisture from their food.

According to the Federal Government’s Threat Abatement Plan for Rabbits (Department of Environment and Energy, 2016) a rabbit density as low as 0.5 rabbits per hectare may inhibit the regeneration of plants and cause “severe” ecosystem damage.

Rabbits hide from predators in scrub including blackberry bushes or fallen logs.  These are important areas to look for evidence of burrows and warrens.  Warrens are usually within 150-200 metres of the food source – grassland, crops and other softer, palatable vegetation.  The rabbits stay within this area unless dispersing due to food scarcity or an increase in population density.   You could set up some wildlife cameras to check what’s going on at the site of the scratchings.  There could be other culprits such as bandicoots or deer.

If it is rabbits, unfortunately their rapidly growing populations attract foxes, wild dogs and cats which then prey on native fauna as well.  It should be noted that working to reduce the number of rabbits on your property, without attempting to reduce populations of feral predators that are also present, can lead to an increase in predation on native fauna.  Native predators such as wedge-tailed eagles, spotted-tailed quolls and dingoes may also be preying on your feral rabbits as an alternative to the less numerous native prey.

Rabbit warrens can become extensive if left unchecked and the burrowings degrade the land, causing compaction and erosion.  Bare patches of soil are vulnerable to further erosion by wind and water.  Well done for spotting the scratchings early.

The main breeding season is late winter to early spring and usually coincides with rainfall when fresh vegetation is readily available.  Warrens are passed from one dominant female to the next. Therefore, finding and destroying warrens during winter is one of the methods of reducing breeding opportunities in spring. 

Rabbits are listed as a key threatening process for over 300 threatened native species. It was back in 2002 when they were put on Schedule 3 of the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 due to the devastating impacts of competition with native fauna and land degradation.  The NSW Scientific Committee also recognised that rabbits were likely to cause species populations and ecological communities that are not currently threatened to become endangered.  

Well, we’ve painted the picture of why it is crucial to try to reduce rabbit populations across farms and native habitats.  Mapping the location and extent of the problem on your site is the first step.  

There is a very useful tool called RabbitScan RabbitScan > Home that I think will suit your needs.  It’s a free, purpose-built resource anyone can use to record observations of wild rabbits in their local area. You can create personal, private group or public records.  It’s now used by landholders, Landcare groups, community groups, local councils, professional pest controllers and biosecurity groups. You can use the website or mobile app version to record:

• Rabbit activity (such as sightings, scat and warrens).
• Damage caused by rabbits, such as soil erosion.
• Control activities undertaken (such as warren ripping outside breeding seasons).
• Disease noted in rabbit populations (such as myxomatosis).

RabbitScan is part of the FeralScan resources.  FeralScan is a website and app where a variety of pest records can be uploaded relating to foxes, pigs, feral cats, cane toads, deer and more. Collating these citizen science records from the field can help guide future regional and state-wide pest management programs.  

Managing vertebrate pests can be a contentious subject bringing ethical debate across different communities.  Understanding the methods of trapping and euthanisia available can help you as a property-owner, or your Landcare group make an informed decision. 

There are several stages in addressing feral animal problems.  Evidence of the pest species’ presence, their estimated population size and their impacts are put together into an integrated, adaptive pest management plan.  Local Land Services can assist you with this.  The pest control strategies are chosen from low to high intervention levels and depend on the ecology of your site and the resources and time you have available.  

Remember that every bit you can do helps in keeping rabbit population sizes as low as possible, which in turn helps native flora and fauna.  Even keeping records of evidence and impacts on the app is making a contribution.

You may be interested in this video from Local Land Services about the pest animal traps available:

Removing pests from peri-urban areas https://youtu.be/QJKpgjezCII?si=U8Rxes8xEL-sS67G

References

Trudy Sharp and Glen Sounders, 2012. Code of practice for the humane control of rabbits. Model Code of PRactice. PestSmart website: <https://pestsmart.org.au/toolkit-resource/code-of-practice-rabbits>.