Q1 I’m worried an eagle might take my pet dog. What can I do?
A1 Depends on the type of pet, where it is and where it wanders. Anything smaller than a very large cat (about the eagles weight) is in the usual prey range so if it is exposed away from the house and away from you it can happen. But it still has to coincide with a somewhat desperate eagle. Swooping down to investigate is far more common than an attack. If something is aware of its surroundings, isn’t intimidated and doesn’t run its less likely to be attacked. That’s one reason attacks are inconsistent from animal to animal. Basically an eagle needs surprise to have a successful attack. Medium sized dogs are often swooped at because the eagles recognises them as competitors and want them to go away but they may be near the prey range so a desperate eagle will want a better assessment. The largest dog I know to have been killed is a Prince Charles Spaniel but its usually Jack Russels and miniature poodles that go wandering on their own (apparently they forget there is a higher power out there). Although talked about a lot its pretty rare.
Q2 How can I help with raptors in Tasmania?
A2 There are many things you can do from helping protect habitat or reduce mortality by writing to councils, politicians and the regulator (eg DPIPWE) about developments, rodent poisons (check the Landcare Tasmania website), firearm vandalism and windfarms, to throwing carcasses off the road that raptors are eating (where its safe to do so), to checking under power lines and poles for dead raptors and reporting them to1800RAPTOR. So TasNetworks can make that section bird-safe. If you join a bird organisation such as Birds Tasmania or a raptor specialist one such as BirdLife Australia Raptor Group you may be able to get associated with specific research and conservation projects. Simply googling research on raptors in Tasmania can give you some options. Many researchers are happy to help people get started on raptors. The Where Where Wedgie citizen science project run by Nature Trackers is a great example. If you are interested in raptor rehabilitation (includes rescuing injured raptors) Raptor Refuge can help directly or put you in touch with the Raptor Rehabilitation Coordinator for Tasmania or you can contact the Raptor Rehabilitation facebook page. Raptor Refuge hosts a reporting number (1800 727867) for dead or injured raptors which can then be retrieved and rehabilitated or post-mortemed.
Q3 I haven’t seen our local eagles in a while. Should I be worried?
A3 Adult eagles have very large home ranges and at different times of year will concentrate on different parts of it either for different food or because they need to reassert territory boundaries. Once young are strong on the wing often the family moves a bit away from the nest but in winter the adults will drift back to get organised for breeding. Young ones eventually disperse. Those processes can produce inconsistence in where they go over time and therefore when and where they are seen.
Q4 A hawk is chasing my chooks. What should I do?
A4 Beyond scaring the hawk right then or locking the chooks up for a few days to break any pattern the obvious thing is to build a hawk-proof pen for them. There are many modern nets good for the job. Raptors do not tear their way in but may take advantage of a hole so do a good job. The next best thing is to give the chooks lots of shelter as a dense cover crop (some people plant mixed bird seed) and provide things they can dive under and hide, their natural defence. Some roosters are good guards as are some dogs. After a while there will be selection for alert survivors amongst your chooks. There are now sprinklers designed to suddenly switch on when triggered by movement such as a hawk landing on a post or hutch. That sudden, noisey jet of water can frighten off an exploring young hawk, the usual culprits. Not all hawks around chooks are interested in the chooks. Many hunt rats and sparrows but the chooks will panic regardless. If you have unguarded free-range chooks you will loose some and its unreasonable to expect such poultry to not be of interest to predators. After all, they stand out compared to more natural prey.
Q5 How can I get rid of rodents without using harmful poisons?
A5 Its almost impossible to actually get rid of rodents but relatively easy to get rid of the problem they cause. The first thing is to think hard about what that problem actually is. Are they damaging things or just annoying? The best thing is to better seal the place you are concerned about. You can then see the scale of the problem you have to reduce. Control is invariably a case of reducing numbers to a point they are no longer a problem. The Landcare Tasmania has an extensive web site discussing options to dangerous poisons. There are many traps from old fashioned (but still good) snap traps through cage traps, electric traps the rodents enter and pitfalls that fit the top of buckets. There are also many baits. The most worrying are the second generation anti-coagulants with active ingredients such as brodifacoum or difenacoum (eg Talon and Bromokil), often advertised as “single dose” that can also easily kill animals eating the rodents. They also accumute and don’t readily break down. First generation anti-coagulants with coumatetralyl or warfarin as active ingredients (eg Racumin) are less dangerous and the new products using salty baits (eg Ratsak Naturals) are far less dangerous with secondary poisoning. Read the labels and do some homework on the active constituents/ingredients (usually on the front of the packet). Also remember some of the rodents you may have especially if you live in the bush might be native rodents that are protected. Baits, whatever they are, should also be placed so other animals than those you target have no or minimum access.
A low level ongoing trapping program usually prevents mice from building up and getting out of hands. Individual rats can be much harder to deal with but pick a fine setting trap and watch what the rats are interested in eating at the time and use that for bait. A good default bait is a some rolled oats mixed in peanut butter. Be persistent.
Q6 I have an eagle swooping at my livestock. What should I do?
A6 Eagles swooping at livestock too big to for prey are sometimes simply curious youngsters encountering new animals but can be more experienced birds trying to move the stock to help flush prey such as rabbits or hares. If it is just a very occasional problem it just might be a territorial male showing off to his mate during courtship (sound familiar?). Regardless, if the stock are scared enough to injure them selves it’s a problem and best to break the eagle’s habit by moving the stock temporarily and/or be aggressive at the eagles whenever you can. Teach them where the stock are is bad news. Some stock guard dogs are bred for this.
Q7 One of my chooks was killed and the head is missing. What did it?
A7 Chooks are pretty easily killed so sometimes a much smaller animal can be responsible, and the head is all they can eat. The head is actually a very tasty morsel with its fatty brains and lots of blood so just a missing head is not diagnostic. Also the chook may have been scavenged, the head being eaten ‘after the fact’. Generally a medium sized hawk such as a brown goshawk might only eat the head and neck (pretty well a full meal for them) but that also applied to cats and quolls. If you skin back the neck band back area you may find puncture wounds and that can be evidence of whether it was actually killed and what killed it. If the chook was indeed killed there will be much bruising around the punctures. If it was dead before being eaten there will not be bruising. The number and position of punctures can show if it was tooth or claw (most raptors kill with their feet). Take photos and send them in.
Q8 Can I put up a nest box for owls? Where can I get one?
A8 In Tasmania owls rarely use nest boxes probably because there are still enough tree hollows. The internet has many owl nest box designs. There are lots for barn owls. Increase the dimensions 50% for masked owls (larger than barn owls) and halve them for boobooks (smaller than barn owls). Brush possums take over most boxes intended for owls so think about privacy (masked owls are much shyer than barn owls) and a place possums cant get to. Owl nest boxes are not available commercially in Tasmania.
Q9 How can I attract raptors to my garden?
A9 Make it attractive to small birds (there is much written about making gardens better for birds) and don’t use anti-coagulant rodenticides (especially second generation) and you will be visited by collared sparrowhawks, brown goshawks and maybe grey goshawks and owls, especially in late summer/autumn. Raptors are wary of people so actually getting them into gardens for more than a brief visit is hard. Better in some ways to get some binoculars and find the local places they regularly visit. In a very large back yard a feeding station with fresh meat can work although so many other animals and birds (and wasps) will also take the food. An old orchard can hold rabbits, rats and be very attractive to birds which in their turn interest the raptors.
Q10 What would be the best ‘offset’ for eagle deaths at Tasmanian windfarms?
A10 According to commonwealth law, offsets can be direct or indirect. The best are surely those directly compensating for eagle s deaths at windfarms by saving eagles somewhere else. Making power distribution lines and poles bird-safe (eg by insulating bare wires on pole tops, adding over-pole wooden perches to very dangerous poles and adding flappers to wires) seems the obvious offset.
Q11 Is 1080 a danger to our raptors? What about Pindone?
A11 1080 is essentially a concentration of a plant defence chemical found in Gastralobia. As such it has been with our raptors for hundreds of thousands of years before Tasmania last became an island and they have adapted to it through traces in their prey. Wedge-tailed eagles, the raptor most usually scavenging after 1080 operations for wallaby and rabbits, have an extremely high resistance to 1080 and there are no records of them (or indeed any other raptor) dying in Tasmania from 1080. 1080 is metabolised by the body and excreted as it breaks down. It biodegrades by microbe action and does not accumulate. The bad press 1080 gets is largely due to dog’s great sensitivity to it. Being northern hemisphere animals, dogs have almost no evolutionary exposure and almost no resistance to 1080.
Pindone is an anti-coagulant rodenticide rebadged for rabbits, is accumulative, toxic to raptors and a real risk through secondary poisoning. It is used near people instead of 1080 because poisoned dogs can be treated (with Vitaman K) whereas dogs cannot effectively be treated for 1080.
Q12 Are tawny frogmouths owls?
A12 Tawny frogmouths are a type of nightjar that mostly catch things on the ground. Unlike owls, they do not have clutching talons so must kill things with their beak. This limits them to prey they can swallow whole. That makes poisoned mice very dangerous for them because the frogmouths not only get the poison the mouse has digested but also all the other bait left in the gut.
Q13 Are all Tasmanian raptors native?
A13 Yes all Tasmania’s raptors are native (or indigenous). The wedge-tailed eagle and masked owl subspecies here are endemic (found only here). A peregrine falcon nest in Tasmania is the oldest record of a nest of any bird anywhere in the world. They have been breeding here for at least 19600 years, measured from C14 dating of mummified peregrine carcasses at a nest.
Q14 Are any Tasmanian raptors threatened.
A14 To be ‘threatened’(an official term) a species must be naturally rare and suffer human threats or be suffering very high levels of ongoing threats that might lead to extinction. Our wedge-tailed eagles and masked owls are threatened on both State and Commonwealth threatened species legislation and our white-bellied sea-eagles and grey goshawks are threatened on just State threatened species legislation. Being threatened gives some extra legislative protection.
Q15 Are all Tasmanian raptors protected?
A15 Yes – everywhere at all times. The law also protects their nest and eggs. It also means you cannot legally collect or possess dead ones or bits without a permit. That’s to stop people killing them then claiming they found them dead – yes, this has happened. To rehabilitate or research them one must have a permit. However the genuine rescue of injured raptors is allowed (as a duty of care) as long as authorities are notified asap or it is taken to a vet or raptor rehabilitator asap. Similarly, dead raptors can be collected for a museum as long as authorities are notified it has been collected asap (giving them a chance to check it).
Q16 Why is a grey goshawks white?
A16 The grey goshawk is a species found in both a pure white and a grey morphs (forms) in much of forested eastern and northern Australia and parts of New Guinea. The white morph is the only pure white raptor in the world (although strictly speaking some have very feint grey flecks and bars) and the grey morph is a beautiful grey/blue. The white form seems dominant and when isolated the species breeds out white, as it has in Tasmania. Being white seems no disadvantage because when hunting alert prey the species is very sneaky, often perching still in the canopy of dense trees completely unnoticed. They mainly hunt by this ambush technique. When perched or flying openly they are very obvious but then they are either inexperienced juveniles (with greenish yellow eyes) or adults (red eyes) not hunting wary prey. Adult males sometimes perch in obvious places using their stark colour to advertise their territories. Unfortunately this is sometimes on a power pole and can lead to electrocution.
White morph grey goshawks are not albinos (which would have soft pink eyes and legs whereas the goshawks have bright yellow legs) but are a fixed form of leucism or extreme lack of pigment.
Q17 How come a bird perched on a power conductor (line) does not get electrocuted?
A17 While just perched on one wire there is no motivation for the electrons go through the birds’ body (no lower voltage path to flow to) so electrons choose the path of least resistance and continue to flow along the wire. To be electrocuted on a wire the bird has to also earth – to have the power flow through it into somewhere with lesser resistance such as the ground (hence the term to earth). Touching two wires will have the same effect by creating a circuit electrocuting the bird.
Eagles usually get electrocuted by crashing into two conductors – they are big enough. If they only hit one they may still be injured but not electrocuted. So collisions of eagles with power lines often result in injury plus electrocution.
Power distribution lines are particularly dangerous because they have sufficient voltage to electrocute, are close together so a circuit can occur between them, are close to poles so earthing can occur, are thin enough to be easily missed by birds and low enough that they are in many flight paths. Also they are very common. Although they carry very high voltages transmission lines do not meet most of these other criteria for high risk.
Q18 Why are female raptors bigger than males?
A18 This phenomena is called reversed sexual dimporphism (RSD) and some species other than raptors exhibit it. But its unusual – why it is called reversed (ie different from the usual). Not all raptors have obvious RSD are but all Tasmanian species do except for the Tasmanian mopoke (aka southern boobook) the sexes of which are similar size. There seem a mix of basic reasons for RSD. Large females can better retain heat during incubation, lay more or bigger eggs (than small females) and are better at defending the nest. Small individuals are more efficient flyers and there fore better at patrolling territory boundaries. There is a correlation between the degree of RSD a raptor species has and whether it takes hard to catch prey, the larger the degree the harder the prey. A simpler version of this is that a species with a large SD will have less direct competition between the sexes and be able to occupy a wider niche and perhaps squeeze out other competing species. And the fact it is better to have the female the larger gives RSD. The Tasmanian masked owl and our grey goshawks have some of the largest RSD of any raptors.
Q19 Why are juvenile raptors larger than adults?
A19 Just before they fledge, juveniles of many raptor species are heavier than their parents but much of this is fat and lost quickly. But all juveniles are larger by feather dimensions (eg tail length, wing span) than adults giving them a lower but less risky flight performance. Their feathers are also more supple meaning they can absorb a few prangs while learning, without breaking feathers.
Q20 How successful is raptor rehabilitation?
A20 Considering survival of the raptors it depends a bit on how specialised the species is. At its very best raptor rehabilitation can give released birds a survival rate comparable to wild ones of the same age. But not much rehabilitation is to that standard and most released raptors have lower chance of survival than others. That is why it is important to mark released birds so that if they are found again their identity can be traced to rehabilitation and methods improved. In Tasmania raptors about to be released by most rehabilitators are leg banded to monitor survival rates. . Some rehabilitation programs outside Tasmania radio or GPS track released birds to get good data on survival and fitness.
Considering its impact on the conservation of wild populations, raptor rehabilitation has very little direct impact since such a low proportions of any population is are dealt with. About 0.1% (1/1000) of Tasmania’s wedge-tailed eagle wild population is released each year or in every 10 that come in.
Considering public engagement, raptor rehabilitation is a resounding success. It is also generally successful on animal welfare grounds.