Category: HawkTalk

Arrival of Red-Tailed Hawk 24-2154

While the patients presenting to the Wildlife Medical Clinic are typically injured or ill in some shape or form, we do sometimes receive patients that are clinically healthy. This was the case for a juvenile red-tailed hawk who was brought to the clinic on October 3, 2024. This hawk, patient number 24-2154, was brought in after it was found by the side of the road, unable to fly. The finder noted that the hawk still wasn’t moving but seemed to be improving during the drive to the clinic. When we did our initial physical exam on the hawk, everything looked normal, with no signs of any wounds or fractures that might have contributed to its inability to fly. The only thing we found was that the hawk had a very large and full crop. Why would a full crop cause this hawk to not be able to fly? Let’s take a brief look at the anatomy of a bird’s digestive tract to find out why.

Avian Digestive Tract

Birds have a slightly different digestive system than mammals do, especially when it comes to their esophagus and stomach. In general, food will pass from the mouth through the esophagus and its associated crop before entering the two-part stomach and then moving into the intestines. The crop is an out-pouching of the esophagus that is used as a temporary storage location for food. This is an important feature for birds who need to regurgitate their food to feed their young. The storage capacity of the crop is also helpful for birds that want to quickly grab a meal and then move to a safer place to digest it. The stomach of birds is divided into the proventriculus and ventriculus. The first portion, the proventriculus, contains cells that secrete mucus and glands that secrete digestive enzymes and gastric acid. The acidic environment here is especially important for partially digesting bone from the diet, which is an important source of calcium for carnivores. The second portion of the stomach is the ventriculus, which is also known as the gizzard. This portion of the stomach is thicker and more muscular than the proventriculus, and it helps to break down the food into smaller pieces. Many birds will ingest grit, small pieces of sand or stone, to help the proventriculus grind and further break down food material. The ventriculus is also the area where indigestible materials like bones, fur, and feathers are trapped and formed into pellets or casts that will be regurgitated. The ingested material will then pass through the intestines, allowing the absorption of nutrients that the bird needs before it is ultimately expelled as fecal material.

Red-tailed hawk diet

The gastrointestinal anatomy of birds differs between species depending on what type of food they are eating. Red-tailed hawks are a type of diurnal raptor, meaning that they are carnivores who do their hunting during the daytime. In the Midwest, they mostly eat small to medium mammals, such as voles, mice, squirrels, rabbits, and some birds. They are opportunistic hunters, however, and will eat a variety of prey items of different sizes. Red-tailed hawks can swallow small to some medium prey items whole, but in cases of large items, they may instead be taken to a perch to be eaten slowly. These raptors have a crop where they are able to temporarily store food and begin the process of digestion before it reaches the stomach.

Exam Findings

Based on its otherwise normal physical exam and large crop size, red-tailed hawk 24-2154 was suspected to have eaten a very large meal that prevented it from flying away properly. The large nature of the crop and the added weight likely caused some balance issues that made it much more difficult for the hawk to be able to take flight. The patient was kept overnight to monitor if it was digesting its prey appropriately and to make sure there were no other signs of injury or infection present. The patient had a DVM exam on October 4, 2024, where the crop size was back to normal, and the patient was completely healthy. The patient was flight tested outside of the clinic on a creance, which is a long weighted line that was attached to equipment placed through removable anklets we placed on the hawk. The patient exhibited normal, symmetrical flight and was approved for release. The hawk was released the following day near where it had been originally found a couple days prior. While this case involved very minimal interventions, this was still a very rewarding case to work on, as the patient made a quick recovery to normal function and was able to be released back to the wild right away.

References:

https://birdsoftheworld.org/bow/species/rethaw/cur/foodhabits

Ritchison, G. (2023). In a class of their own: A detailed examination of avian forms and functions. Springer Cham. https://doi.org/10.1007/978-3-031-14852-1_5#DOI

Written By: Sarah, Class of 2027

Fear Free Approach

In recent years, many veterinary practices have shifted towards a new approach to helping animals feel safe and secure in the clinic. These techniques, called “Fear Free”, aim to decrease stress and fear responses in animals as much as possible, while still being able to conduct adequate exams and treatments. The Fear Free approach aims for a patient-led experience, allowing animals to move about freely with minimal restraint, using relaxing sedatives if needed, and avoiding things that typically induce fear, such as metal exam tables, white coats, and loud noises.

Balancing Act while treating wildlife

In the Wildlife Medical Clinic, creating an environment that minimizes fear and stress is essential for the wellbeing of our patients. In many cases, low stress handling can mean the difference between life and death for wildlife. Uncontrolled stress in animals can suppress immune function and delay healing times, which makes recovery exponentially more challenging for patients. This effect is even more exaggerated in our wildlife friends, as a vast majority of the animals we see in the clinic have no prior experience with humans or handling, and consequently view us as terrifying, dangerous predators. However, this fear response is something that we want to preserve in wildlife, as animals that become too acclimated to humans may not be able to be released back into the wild. Thus, the Wildlife Medical Clinic works to ensure that an adequate balance is upheld when treating wildlife – animals should be handled in a way that creates the least amount of stress as possible, while also ensuring the animals do not become too comfortable around people.

Low Stress Techniques for Wildlife

While wildlife patients are in our care, there are numerous strategies that Wildlife Medical Clinic volunteers employ to uphold a low-stress environment for our wild friends. First, direct handling of wildlife species is restricted to only what is medically necessary. This may be for physical exams, medication administration, or wound care. Since this is the most stressful time for our wildlife friends, it’s important to remain hands-off until required. Direct handling of wildlife will always be stressful to some degree, but multiple techniques are implemented to promote a calmer experience while exams are conducted. For example, most bird species, from finches to falcons, calm down when their eyesight is restricted. You will often see volunteers using soft towels or pillowcases to cover the heads of birds, and we even have special hoods for raptor species to minimize stress. Additionally, for extremely stressed patients, sedatives can be administered to decrease the animal’s fight or flight response, allowing for a calmer patient and easier exam. Volunteers also always keep their voices low and calm while handling wildlife, to avoid startling patients with loud noises.

You can see low-stress techniques being utilized throughout the Wildlife Medical Clinic, even when animals are not being directly handled. All animals receive their own cages to rest in while they recover. These enclosures can be covered by a towel or blanket to block sightlines and help the animal feel secure and safe in their space. Additional hiding places and enrichment may also be included inside the cages as an added means of security for the patients. Patient holding is located in rooms separate from the rest of the clinic, which helps to minimize the amount of noise and commotion the animals are exposed to. Ambient noise makers are also used inside of these rooms to mimic the natural sounds of the outdoors while they recover.

While being removed from the wild can be quite stressful for our patients, the time and dedication of our volunteers to ensure their stay is as low-stress as possible helps aid in the success of the Wildlife Medical Clinic, allowing animals to recover quicker and be returned to the wild safe and sound.

Written By: Kayla, Class of 2028

Barred owl Information

The barred owl (Strix varia) is a larger owl species found in North America. They are part of the family Strigidae, known as the “true owl family.” These brown-gray owls are native to Eastern North America, most often found in mature forests and woodlands. Their main diet is small mammals, but barred owls are known as opportunistic hunters and have been seen consuming other birds, reptiles, amphibians, and even a variety of invertebrates. This is one of the more common owl species that we see here at the Wildlife Medical Clinic.

New Patient Arrival

In fact, on August 20, 2024, a barred owl came to the clinic and was in poor body condition, had external parasites, and signs of inflammation and damage in both eyes. During our exam, we found a clavicle fracture that was confirmed with x-rays, which would partly explain why this bird was not in the greatest condition. The clavicle is an integral part of the bone and muscle structure that gives birds the ability to fly. Meaning this individual was not able to hunt for prey due to this injury. These fractures, however, are very easily healed with cage rest. The next issue of concern on the list of problems this barred owl had, was its eye inflammation and damage. We needed to assess whether it had the ability to see. On August 23, we consulted with the Veterinary Teaching Hospital’s Ophthalmology Department, where it was confirmed that in the right eye there was a portion of the retina that was detached, which led to the eye being non-visual. The left eye had some mild inflammation and damage but was determined to be mostly functional. The plan moving forward after this exam was to see if the ongoing inflammation in the right eye would resolve, and if not, the eye would need to be removed via a procedure called an eye evisceration.

Potential Surgical Option for this patient

In general, animals that come to the clinic and are found to have non-functional eyes are given a poor prognosis or ability to survive in the wild. Most of the animals we treat in the clinic either use their eyes for hunting or to watch for predators. Without vision in either one or both eyes these survival instincts are no longer intact, and the animal would either not be able to find food or would be at a greater risk of predation. With owls, due to their nocturnal nature, they rely more on their hearing while hunting at night, than their sight. Because of this, owls are a candidate for the eye evisceration surgical technique to treat non-healing or non-visual eyes.

With this barred owl, the inflammation unfortunately did not resolve, even with medication. Therefore, on the 29th of August, Riley Dunwoody, our junior student manager, performed the eye evisceration surgery under the guidance of our Director, Dr. Lewis. For this procedure, the very front part of the eye, the cornea, is removed and the inside of the eyeball is removed. The outer structure of the eyeball is left intact and the eyelids are sutured closed around it. The outer structure of the eyeball is left intact on purpose. In owls they have a structure known as scleral ossicles within the structure of their outer eye. This gives their face and head the structure it needs to properly allow for sounds to enter the ear. If the entire eye was to be removed, then the face would lose its normal shape, and the owl would lose its sharp ability to hear their prey.

Recovery and Next Steps

Post surgery, the patient recovered well, their weight significantly improved, and the clavicle fracture showed promising improvement with the formation of a callus (area of extra mineral or bone growth) which indicated the bone was healing. It was decided we would flight test this patient to see if they were ready to be transferred or released. Temporary equipment called removable anklets were placed on the bird’s legs. Then small strings called jesses are placed through the anklets and connected to an extender that is then connected to a creance line. The creance is a light weight, long line that is connected to a weight. This technique can be used to safely evaluate a bird’s flight or to help them build up strength flying to condition them for release. Creancing allows the bird to fly but for a limited distance, usually up to 150-200 feet but we start off at shorter distances and increase the length and number of times they fly on the creance, as they build up strength. However, for this purpose, it was just used to evaluate the Barred Owls flight capabilities. When this bird was creanced, we saw that it had flight capability but would need a lot of conditioning before it was ready to be released. Because of this, we determined that the most beneficial next step would be to transfer to another licensed rehabilitation center that has access to a large flight cage. This would be the best way for this individual to regain strength to fully fly again before it is released back into the wild.

After a month with us, on September 24, we successfully transferred this barred owl to a facility with a large flight cage, where it continued its rehabilitation. Our friends at Illinois Raptor Center allowed this patient to recondition in their large flight cages, and on November 19, Riley had the privilege of releasing this patient back in their home territory!

Written By: Riley, Junior Student Manager and Class of 2027

Great Horned Owl, Bubo virginianus

The great horned owl, Bubo virginianus, is found across the majority of North America. Here in Illinois, they are found across the entire state. They are very adaptable and can be found in trees in a variety of habitats, including forests, prairies, and some urban areas. They are easily identified by the tufts of feathers over their ears, which resemble horns.

Arrival to the Wildlife Medical Clinic

Towards the end of August, an adult great horned owl was presented to the clinic by a good Samaritan, and all that was known about it on presentation was that it was unable to fly. On the initial exam, the patient was thin and had severe diarrhea. Radiographs were taken, which confirmed that the patient did not have any fractures. A fecal was run, which showed the patient had a very heavy endoparasite load of capillaria. The patient was treated with a round of dewormers and antibiotics. A creance flight test was also performed, which is where the patient wears falconry equipment and is temporarily attached to a long line that is connected to a weight. Performing creance allows us to evaluate the patient’s flight while being able to easily retrieve them for continued care. At the initial creance, the patient would only defensively posture and did not attempt to fly.

A few days after treatment, a recheck fecal was performed. The capillaria load was lower but still heavy, and another deworming was performed. There is a fungus, Aspergillus, in the environment that birds can be susceptible to if they inhale the spores while they have a compromised immune system. Since there was potential for this patient to have a compromised immune system, a short prophylactic course of an antifungal medication was started as well. The patient had started declining in weight by the end of August and was not as interested in food, so the patient was supplementally fed for several days to prevent any further weight loss. 

Continued Care

A recheck was performed on a fecal sample in early September to re-evaluate the patient’s parasite load, and there were now fewer capillaria seen, but another endoparasite (coccidia) was also seen. Yet again, another dewormer was given for the intestinal parasites. A blood sample was also taken at this time and sent to the Veterinary Diagnostic Lab at the University of Illinois, and it was found the patient had moderate levels of three different blood parasites, including Plasmodium, or avian malaria. At this point, a daily anti-malarial drug called pyrimethamine was started. The goal for treatment for these blood parasites is to get them to low levels, as the patient will never be completely cured of them. A fecal and blood sample were rechecked about a week afterwards to monitor the patient’s response. The initial two intestinal parasites were not present, but another type of intestinal parasite (strongyle) was seen. Another dose of a dewormer medication was given. There were no major changes seen on the blood sample, but the blood parasites that were present can require a lengthy period of treatment to get them adequately controlled. At this time, the amount of food the patient was being offered was also increased to help keep weight on the patient, as all the food offered was being eaten.

Turning the Corner and Gaining Strength for Release

Towards the end of September, a recheck was performed where blood and fecal samples were taken and another creance session was completed. The fecal showed a very low strongyle load. It was elected not to administer another dewormer at this time as it was a low number of parasites, and the patient will naturally come across these parasites in the wild. The blood sample showed lower levels of the blood parasites, and it was decided to stop the anti-malarial course the patient had been on, as the levels were low enough for the immune system to keep them in check.

We tried another creance session and this time, the patient flew short distances and had symmetrical flight. This patient was getting stronger and healthier, so it was time to move them to an outdoor flight cage. This allows the patient to move around in a larger space and for us to access their flight better before considering release. After monitoring the patient in the outdoor flight cage, we decided to transfer them to another licensed rehabber in early October to continue monitoring the progression of healing while allowing the patient to fly in an even larger enclosure and gain more strength before returning to the wild.

Written By: Angela, Class of 2026