Hello all! Tonks & Dora are about two-thirds of their way through the season and Lily is flying outdoors now so we'll begin transitioning soon!
Today I wanted to talk a little bit about medical issues and injuries. As a veterinarian, this is a subject that is right in my wheelhouse. Unfortunately, my experience is that it's something many new falconers are ill-prepared to address.
The truth of the matter: being a raptor is a hard living and the only ones not getting hurt are the ones not doing any hunting. Remember, raptor mortality in the wild is 80-90% and there is a narrow window to catching a minor problem before it becomes a major one.
We won't be able to comprehensively address this very broad subject here, but let's hit on the most common issues, grouped by problems at home and problems in the field. (For those who like medical reading, a more comprehensive discussion can be found here.)
Problems at home
Like most other animals, proper husbandry can prevent nearly all of these issues:
Caused by the fungus Aspergillis fumagates, the most common form is infection of the respiratory system. Untreated, it is usually fatal within 10 days and arctic species like Gyrfalcons, Goshawks, and Snowy Owls seem to be the most susceptible. While ubiquitous in the environment, primary exposure is via moist organic matter in the raptor's environment and prevention is as simple as keeping the mews clean and dry.
Bumblefoot is a collective term for bacterial infections of the foot secondary to either inadequate perches or small defects in the skin of the foot that then seal over, trapping the bacteria beneath the surface. Raptors are very good at healing skin lacerations but have poor blood supply (and thus poor immune response) to their distal legs and feet. Further complicating this condition is the fact that purulent material (pus) in raptors does not occur in liquid form but rather rubbery nodules that have to be surgically removed. Prevention is again they key -- utilizing appropriate perch surfaces and treating minor foot injuries aggressively. Surgery, antibiotics, and even orthotic shoes are necessary to correct advanced cases.
Here is a Prairie falcon that fractured her left tibiotarsus and subsequently developed bumblefoot of the right foot because she was supporting her weight entirely on the right side for a week prior to presenting at the vet. Note the swelling of the right foot and secondary sloughing of the dorsal skin.
Frounce is a highly contagious fungal infection cause by Trichomonas gallinae. It affects the mouth and the throat, forming white or yellow plaques that often need to be surgically removed. Pigeons commonly carry Trichomonas in their upper GI tract and are thought to be the main source of infection.
Prevention: don't feed pigeon heads or GI tracts.
Sour crop is simply a bacterial infection of the raptor's crop, often caused by damage to the crop lining or sub-par food sources. The crop does not have the antibacterial properties of the stomach (stomach acid) and the longer food sits in the crop, the more time bacteria has to replicate and cause problems. Treatment often involves flushing out the offending material and it's attendant bacteria, often followed by antibiotics. Prevent this by...wait for it(!)..... only feeding high quality food and not over-feeding.
West Nile Virus(WNV)
One of the few avian problems that's been widely publicized, WNV is invasive to the U.S. and attacks a bird's nervous system, respiratory system, and spleen. Raptors that survive an infection often have lingering neurological and respiratory problems that end their hunting careers.
Vaccination is quite effective and I recommend all falconry birds be vaccinated with the Merial Recombitek equine WNV vaccine.
Problems in the Field
This category is largely comprised of injuries that occur while hunting. Flying is a dangerous way to make a living - some of these can be avoided and some cannot. If and when any of these problems do occur, the key is to keep the bird calm, cast her so she doesn't make the injury worse, clean the wound if applicable, and seek medical attention promptly.
This is the biggie - one of the most common causes of mortality in wild hawks. It can be prevented in falconry birds by simply avoiding fields with utility poles that are not of bird-safe design. Utility companies have gone to great lengths to correct this problem but there are still dangerous lines out there.
( For those of you with a couple hours to burn, here's the standard best practice construction guideline that utility companies use for both new construction and retrofits of existing lines. If you can make it through the first hour, there are pictures in the second half of the paper, I promise!)
Here is an electrocuted Prairie falcon image from Montana Fish & Parks. The falcon's foot is still embedded in the pigeon.
Fences and blunt impact trauma
Blunt impacts are less of a problem for falconry raptors than wild ones - falconry raptors usually impact a tree chasing squirrels or get clothes-lined by a branch while riding a jackrabbit. These can still be fatal though, either by head trauma or cervical fracture.
Fences, particularly barbed wire ones, are a bigger problem as they're very hard to see in flight and are ubiquitous. Fence impacts often result in either clothes-lining as above or impressive lacerations. Choosing fields where you can stay at least 100yds away from fence lines is your best bet in terms of prevention.
Tonks hanging up on a fence (at 2:20). Note how she doesn't try to do anything to make this worse - she waits for help.
This impact injury can happen at home just as easily as in the field. The following diagram marks the most common fracture locations in hawks (for falcons, add foot and toe fractures as well). Keep calm, cast the bird, and get thee to a vet! Nylons or pantyhose work great for casting a bird in the field and should always be carried in your hawking bag.
This is actually the Prairie falcon used in the bumblefoot example above. This left tibiotarsal fracture is a classic over-weight bird + over-long leash fracture as this is the spot most likely to give when the bird bates.
Same fracture in a Harris' Hawk.
Not really an injury per-se, but can affect flight performance. These will be replaced during the molt but repairing these in-season is called imping. Here's a video for those interested: Imping.
These can look impressive but unless they're located on the foot, they'll heal quickly if kept clean and sutured closed. Again, cast, clean, and seek veterinary care.
Punctures and Bite Wounds
If you're flying a cast of Harris' Hawks, they'll eventually puncture each other grabbing at game. If you're flying a solo hawk, bite wounds from the game animal are most common, especially on the feet. Again, the skin heals quickly but bacteria deep in the wound is the real risk here. Clean as best you can in the field and and seek veterinary care as antibiotics are always indicated for bite wounds to the feet.
Dora's foot a few years ago -- I think from a weasel if memory serves.
This is a Goshawk's foot after being bitten by a gray squirrel. Note the spiral fracture and questionable blood supply to the distal digit. This is not my case and is currently under treatment, final outcome not yet known but amputation is a real possibility here.
The talons actually have a bone running through to very near the tip. Sloughing the talon sheath or breaking the talon off expose this bone. If not cared for, one of two things will happen:
a) the bone will recede, even crossing the joint and requiring amputation of the toe.
b) the bone is broken off and the claw will not grow back.
I've seen these mostly in Harris' Hawks (why, I do not know) and Gyrfalcon hybrids.
Here's a Dora talon fracture, also from a few years ago. That white stuff is bone.
The bone is protected with either cyanoacrylate tissue glue or clear nail polish.
This is then covered with heat-shrink tubing to form a lasting bandage
These take six to eight months to heal. Here we are in August, nearly a year later.
This last case was another Harris' Hawk who got her talon bitten off by a jackrabbit. Compare to the photo above and note the bone is missing. This will not regrow.
Healed to the extent it's going to.
I know this was a fairly superficial run-through of a very broad subject. Remember, cast the bird (don't forget your pantyhose!), clean the wound, and get thee to the vet! Modern medicine is really pretty amazing if we can get to things early. Taking a week or two off to allow an injury to heal is a minor blip in a bird's 10-12 year hunting career. Don't risk it! Take the time, make the effort, and you'll be back up and running in a snap.