On our 5 acre property, nightly feral predator visitors included 6 individual foxes and 5 free ranging cats. Probably that is quite representative of the non-native predator density for much of Australia. Measures to reduce the risks to nest box occupants are very much worth considering.
During our first year living on our bushland property, I recorded wildlife camera footage of cats destroying a nest of Scrub Wren chicks just before fledging, outside our back door. That was pretty devastating.
Our nest box-hatched Wood Duck ducklings decline significantly in number during the many weeks when they cannot fly to roost safely in trees. Sleeping on the ground by night, young Wood Duck families clearly are heavily impacted by nocturnal non-native predators. I have recorded numerous foxes snooping around our dam by night during duck breeding season.
By day, all types of juvenile birds are vulnerable to predation by feral predators once they have left their nest box. We regularly see our young Rosella families feeding on grass seeds on the ground, and Wood Duck ducklings similarly forage on the ground for grass seeds, and fresh grass shoots.
I have seen documented evidence elsewhere of free ranging cats taking nestlings from nest boxes, so this is a problem to consider. Also, for nest boxes installed low to the ground, it is likely that the risk to both parents and chicks by cats would be more greater, than for a nest box installed two or more meters from the ground. A cat can easily wait in the shadows and pounce on parents that regularly visit a low-to-the-ground nest box to feed youngsters.
The installation of possum guards on a tree below a nest box will prevent a cat or fox from climbing a tree and accessing the nest. Also for small nest boxes too small for a fox or cat to access from the front entrance, installing a locking mechanism to prevent the nest box lid from being opened is a good option. Better still though, install the box out of their easy ambush/reach.
While nest boxes do offer occupants some protection against feral predators, they can still be at risk. There are many strategies that can be employed to reduce the predation risk to occupants (by day and night), or to parents feeding hungry chicks by day. However once youngsters have left the safety of a nest box, they are extremely vulnerable to feral predators, by day and night. Young birds are often not very street-smart, or startle as quickly as their wily parents.
It’s also important to remember that most Australian native bird species do not nest in tree hollows (or nest boxes), and so are very vulnerable to predation by feral predators, particularly by free ranging cats.
Please keep your cat indoors, or install an outdoor cat run to prevent impacts to wildlife.
Control options: For those on larger rural properties, shooting feral predators is a great option. However note that the various predator individuals that visit your property will have schedules that differ to that of the shooter, such that it is unlikely that you will shoot them all. For smaller rural properties such as mine, and urban areas, shooting is not an option for you. Soft jaw foot traps are a great alternative, or to combine with trapping.
Poison: I’m not such a fan, particularly because of the risks of secondary poison. Think native birds of prey, including eagles, hawks, falcons, owls, and also scavenger and carnivorous native mammals. I am also not an expert on the poison options so cannot offer advice on better or worse options. If interested, contact the various conservation NGOs that have programs on cat and fox control, baits etc that also care strongly about wildlife outcomes.
Cage Traps: Cage traps are generally ineffective for all but the silliest and most naive feral predator individuals, such as very young foxes, pet cats and some feral cats. There are some important tricks to setting up cage traps that will improve your success considerably, such as adding soil to cover the mesh of the base, not handling the trap with your bare hands (human scent), tying the bait up high on the back to make the animal have to reach up and so trigger the treadle pad, and dripping sardine oil in a trail towards the trap, and then through the trap to where the bait is installed. Please note that it is illegal (and also immoral) to catch and release foxes in (at least) most states, this is simply relocating the problem to someone else’s backyard.
Soft Jaw Foot Traps: Soft jaw foot traps are legal in at least NSW and WA, I’m not up to speed with the other states. They have rubber pads along the jaw where the animal’s leg is held to prevent injury. The idea is, that you set the traps to catch the feral predator, then put it down once trapped. Or release the non-target animal unharmed, I regularly trap Brushtail Possums who also like eating sardines and chicken, also sometimes the neighbour’s dog that (used to) like to roam. Traps need to be checked regularly – early each morning, and preferably covered by day if left set, to prevent harm to native daytime animals that may become prey if caught, to a native or non-native predator. Stealthily installed with tempting bait, foot traps are a very effective feral predator control method. Your trapping rate will improve as your skill as a trapper improves. This is the method that I use to control feral predators on our 5 acre rural property, where neighbour’s houses are much too close for shooting to be a safe option.
Follow this link a page with information on how to install soft jaw foot traps to control foxes and feral cats. As I cannot add video to this website, I recommend that you look on YouTube for “dirt hole set” videos to watch demonstrations of how to set traps also.
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