Exercising Raptors Back to Health

By Jennifer Guess, Senior Wildlife Technician

Photos by Jenn Guess

Here at California Wildlife Center (CWC) we see a lot of raptors with severe injuries that require many weeks even months of rehabilitation. The raptor family includes all types of hawks and owls. As the birds heal inside the ICU they do not get the daily exercise they would receive in the wild. Due to most raptors lengthy recuperation period, the vast majority need to be exercised at the end of the rehabilitation process to build up flight muscles before they can be released back into the wild.

When a raptor reaches the point in his recovery plan where he is stable and in good body condition he can be moved into one of our large outside aviaries. Raptors fly many miles every day and it is difficult to provide enough space in an enclosure where a bird can get adequate exercise on his own. One method of exercising raptors is to encourage them to fly from one end of the enclosure to the other. The drawbacks of this method is that it can be stressful on newer patients sharing the large flight aviary, and on patients in nearby flight aviaries. Plus, most birds learn very quickly how to navigate the enclosure with as little exertion as possible.

At CWC we use a method of exercising called creancing. During creancing the raptor is caught up from the outside aviary. A hood is placed over the head and eyes to reduce the stress level of the bird. Leather anklets are attached to the bird’s legs, above the feet. The bird is then transported to a nearby open

field. Leather strips, called jesses, are fed through the anklets and hang down below the bird’s feet. A light weight line with a weighted tube is connected to the jesses.

When everything is ready to go, the hood is removed and the bird is let go and he takes flight. He flies across the field and when he reaches the end of the line the weight in the tube starts to add resistance. As the bird drags the weight, he quickly tires out and lands on the ground.

It is important to do a lot of prep work before creancing a raptor. The weight of the tube must be adjusted depending on the weight of the patient. If the tube is too heavy, it could cause injury to the bird when he reaches the end of the line. If the tube is too light, the bird might be able to fly further than expected and into an obstacle like a nearby tree. The line must also be carefully measured before each creancing session. It should be long enough so the patient can gain lift and propel forward before feeling the weight of the tube but it should not be so long that the patient can reach obstacles.

During the flight, important information is being collected. The majority of our creancing is performed by Malibu resident and longtime CWC volunteer, Diana Mullen. She takes careful note of how far each patient flies, how much lift they are able to obtain, whether the wings are symmetrical during flight, and how quickly the bird tires out. She works very closely with our veterinarian, Dr. Duane Tom, and knows the history of each patient before taking them out for creancing. It is important to not push the patient too hard. Sometimes a single flight is enough for a creancing session. Depending on the patient, a bird might have three or four flights in a session. Each piece of information is carefully recorded in the patient’s record so Dr. Tom can adjust their individual plans. Volunteers are able to assist Diana during these creancing tests and all agree that seeing the raptors soar into the air serves as an excellent reminder of why we do the hard work of rehabilitation for these beautiful animals.

Crow Feather Imping

By Alyssa Schlange, Volunteer and Outreach Manager

Crow 1476 after release. Photo by Alyssa Schlange

His tail after having broken feathers replaced. Photo by Alyssa Schlange

The donor feather is inserted into the shaft of the original feather.
Photo by Alyssa Schlange

American Crow number 1476, came to us on May 13th of this year as an orphan with terrible feather quality, suggesting malnutrition due to abandonment. After three weeks of consistent care and steady weight gain the crow was still not able to fly. Dr. Duane Tom, Director of Animal Care, ascertained that the crow would need the full set of wing primary feathers to be replaced, or imped, and possibly full tail primary feathers as well.

Imping is when we take feathers from a deceased patient with good feather quality and insert them into the feather shafts of the living patient under anesthesia. We remove the patient’s bad or broken feathers and glue the new feathers in, which improves the bird’s flight quality. It allows the birds to maintain muscle tone and flight ability while recovering, better preparing them for release when other injuries are healed. Imping is a life-saving but complex procedure, as the donor feather must match the recipient in age, size, and sex. The feathers are carefully inserted at particular angles so that it mimics the degrees of the original feathers that allow the birds to soar.

On June 5th Dr. Tom and his team of preceptors (fourth year veterinary students) imped the crow’s wings in a procedure that took over 2 hours. While 1476’s flight did improve, he was unable to fly directly to the highest perch so it was decided that we also needed to imp the tail feathers so that he could get more lift in his flight. On July 11th, we imped the remaining tail feathers.

After a few days in the enclosure he was okayed to be released. On July 14th, after being in care for 61 days, he re-entered the wild with 14 other juvenile orphaned crows.

West Nile Virus in CWC’s American Patients

Photo by Alyssa Schlange

By Melissa Hartman, Administrative Assistant

Of all the American Crow patients we see, 15% carry the disease.

In 2016, California Wildlife Center admitted 238 local American crows for a variety of reasons—chicks apparently abandoned by their parents, fledglings fallen out of a nest too high to allow them to be replaced, adults suffering from broken limbs and open wounds. But more than 40 of these birds came into our Center with troubling symptoms including a lack of balance both at rest and while mobile, weakness, lethargy, even seizures. West Nile Virus—WNV—is listed as the cause of death on 37 of these medical records.

WNV has hit American Crows particularly hard. In the summer of 1999, the disease first appeared in New York City, where a dead crow at the Bronx Zoo foreshadowed what was soon to come. Within four months, tens of thousands of crows perished over the tri-state area. Tests conducted indicated that for this sleek, intelligent bird, the disease was 100-percent fatal. Many other species, from jays to sparrows to finches, also proved susceptible. Within five years, WNV had spread to the Bay Area leaving millions of birds dead in its wake.

Here at CWC we see a significant population presenting with the telling neurological signs of WNV: limb weakness, head twitching, and paralysis. Our treatment is supportive care.  We use anti-inflammatory medications and maintain their nutritional requirements. Mild cases may recover but sadly severe cases seldom do. Those that recover reportedly are immune to future infections by the virus.

WNV At-A-Glance

  • West Nile Virus can be fatal to humans; less than 1% of those infected
  • However, 80% of infected people will not show any symptoms
  • Flu-like symptoms mainly transmitted through mosquito bites, not through other animals
  • Primarily affects birds, but also bats, horses, cats, dogs, chipmunks, skunks, squirrels, rabbits
  • Vaccines are available for horses but not for people


Standing water is the culprit. Reduce the number of mosquitoes around your home by emptying water from gardening containers, buckets, gutters, pool covers, pet water dishes and birdbaths. Monitor sprinkler runoff as well. The most effective way to AVOID WNV is to prevent mosquito bites:

  • Use insect repellents
  • Wear long sleeves and pants from dusk through dawn
  • Install or repair screens

You can help us reduce the number of American Crow admissions by clearing standing water. Make sure in the coming months when mosquito activity is high, you stay safe in the outdoors and have fun!

With CWC, Love is Owl You Need

By Melissa Hartman, Administrative Assistant

Throughout recorded history and across many cultures, the allure of owls is enduring. Few other birds have inspired so many conflicting beliefs. Owls have been both venerated and feared, considered wise by many, thought to be obtuse by others, associated with witchcraft, medicine, the weather, and even believed to foreshadow birth and death.

Photo by Kim Barker
CWC has helped 31 Great Horned Owls so far this year.

Owls brought to the California Wildlife Center include Barn Owls, Burrowing Owls, and the California Great Horned Owl, which is by far the most common of our owl patients seen!  So far this year, we have treated 31 of these distinctive-looking birds, also known as Bubo Virginianus, with their large ear tufts.  Some people call this a “Cat Owl,” “Winged Tiger,” or “Tigers of the Air” because of their ears.

“Whoville” is the name we give to our outdoor Owl Aviary. Owls stay and are rehabilitated until they can be transferred and released. From Whoville there issues a large repertoire of sounds-deep hoots to shrill shrieks! This year, we took in our first owlet in February, testament the the great horned owl is one of the earliest nesting birds in North America, often laying eggs weeks or eve months before other raptorial birds. This species is strictly monogamous and solitary except for nesting.

What should you do if you find and owlet that has fallen from the nest and is clearly abandoned, or an injured adult owl? Baby raptors will need immediate care from a licensed rehabilitator. Get a box and follow the instructions on the CWC website’s medical emergency tab. Do not offer any food of water.

Please call our emergency hotline number, (310)458-WILD (9453) and contact hospital staff for authorization to bring in the owl or owlet. Remember, it is a federal offense to to keep native wildlife as pets. Their best chance at a new life may include a stay at the California Wildlife Center, and we are dedicated to making that new life happen!

Living With Animals: Over Rescue

Ken White, Board President, California Wildlife Center

California Towhee

Fledgling California Towhee
Photo by Kim Barker

We are nearing the first day of Spring when, to mangle Tennyson’s lovely words, a young humaniac’s fancy turns lightly to thoughts of rescuing baby birds. Say what..?

Spring, the season of rebirth, and we’re already receiving calls from kind-intentioned people who’ve found baby birds, and baby squirrels, out of the nest but apparently unable to care for themselves. Yes, it makes sense to worry but, no, scooping babies up and rushing to our wildlife rehab center is not necessarily the best thing. In fact, potentially it’s “over rescuing.”

Hard as it is, sometimes (even often) the best thing for these babies is to be left alone.

Babies which are almost ready to fly (or squirrels to scurry) often flap and fall. That may place them at risk, but it is not necessarily The End. Often mothers will continue to protect and feed babies on the ground below nests, warding off potential predators (assuming they’re a type mom can handle) and encourage them to take those first flaps (or, for squirrels, first hops).

The cliché that mom will reject babies handled by smelly humans is untrue. If the nest is located where it’s safe to return the babies, do so. Mom will not object.

Common sense has to prevail, requiring your eyes and brain for each specific situation. If the area is heavily trafficked by noisy children, dogs or free roaming cats, then the odds shift radically. But if this is a quiet corner of the yard, and your cats are indoor-only animals (as they should be, please!), then hands-off is probably the best option. Uncertain? You can always call us (310-458-9453, select option 2) to help you make that assessment.

We are here to help. Injured and orphaned native wild animals can be brought to California Wildlife Center. Last year we helped 4,072 native wildlife. But we’re here to help mom, not replace her.

Room for Swallows to Soar

By Denys Hemen, Hospital Manager

Cliff Swallow

A Cliff Swallow eats a mealworm “on the wing.”
Photo By Jenn Guess

Here at California Wildlife Center space has always been at a premium. As the only rehab center in Los Angeles County that rehabilitates baby songbirds, space disappears quickly in the springtime. But, anytime you get a large number of baby birds crammed into a small area many problems can arise. It becomes very hard to keep them clean. Internal parasites can run rampant. In general, just being inside can cause some developmental issues. Birds just want to be outside where they belong! Our swallows were getting anxious to stretch their wings but would continue to eat from our hands inside. They are notorious for their extended weaning period. These trouble makers would constantly escape from their enclosure and fly around the room but were still too young for our large aviary. That’s why we have constructed our fledgling cliff swallow aviary!

This small ( 6ft x6ftx 8ft tall ) but secure aviary allows our younger swallows, who aren’t quite ready for the big aviary yet, to stretch their wings. They have more room to move around and develop at a much quicker pace. Inside their aviary, we have free choice food but some of these young ones haven’t quite grasped the whole self-feeding thing yet. That is where we come in! Every 45 mins we enter the aviary and hold up a juicy worm with tweezers. The swallows swarm around, dive down, and grab the worm from our grasp! This gives them some much needed practice because once in the wild these birds will catch flying insects “on the wing”. We also collect fruit scraps in buckets that are left inside the aviary to attract fruit flies. The swallows practice their hunting skills on these tiny flying insects.

Once the whole group is eating on their own and refuse hand-feeding, we move them to an aviary that is nearly 10 times larger where they develop their flight muscles and prepare to move on to the next step, a release into the wild!

Bumper Crop for Baby Care Unit

By Hospital Manager Denys Hemen

Orphaned birds like this young American robin are placed in CWC's Baby Care Unit while they receive the treatment and diet necessary for them to grow. Photo by Kim Barker

Orphaned birds like this young American robin are placed in CWC’s Baby Care Unit while they receive the treatment and diet necessary for them to grow. Photo by Kim Barker

It was another great year inside of our baby bird nursery at California Wildlife Center.  We are the only wildlife rehabilitation center in Los Angeles County that takes in baby songbirds, baby crows, and baby ravens. Due to this fact, we have to dedicate lots of space to their care.  We added 128 square feet of indoor space to our existing 14 enclosures that are dedicated to baby songbirds, crows, and ravens.  It took our team a lot of blood, sweat, and tears to accomplish but it was well worth it.

We were able to release hundreds of birds back to the wild. There was a wide array of birds that traveled through our doors this summer. There are the most common species we care for and raised: northern mockingbirds, black phoebes, house wrens, western scrub jays, western kingbirds, cliff swallows, mourning doves, dark-eyed juncos, American robins, house finches, bushtits, acorn woodpeckers, California towhees, American crows, lesser goldfinches, and common ravens.

At the height of the season, we were ordering 60,000 mealworms, 1000 waxworms, and 2000 crickets per week to feed the songbirds and 50 pounds of dog food, protein, eggs, and produce per week for the crows and ravens!  Our dedicated team of staff, interns, and volunteers worked 13-hour days to feed all of the open and hungry mouths.

Baby bird season has just ended at CWC.  We put our last group of northern mockingbird babies out in the aviaries last week.  It was a tough summer! But before we even take a breath, 48 baby squirrels moved into the nursery!

Snowshoes in the Summer

California Wildlife Center recently rescued a Northern Mockingbird whose feet were knuckling, meaning she was unable to open her feet to stand or perch.  This was causingbefore and after snowshoes the bird to have to stand on the tops of her toes which were curled under and causing her additional injury.

CWC veterinary staff created “snowshoes” for the mockingbird to retrain her feet to open and allow the injuries to her toes to heal.  The treatment was successful and the bird is now snowshoe-free and on the road to full recovery!

New Aviary Filled with Unkindnesses and Murders

Ravens by Heather Patrice Brown

Ravens and crows enjoy the new enclosure. Photo by Heather Patrice Brown

By Development Coordinator, Heather Patrice Brown

“Squawk!” “Caw-caw!” The new exterior aviary, sponsored by the Wendy McCaw Foundation, is anything but a quiet, peaceful place.  This 8’ x 16’ enclosure currently houses both a murder of American crows and an unkindness of common ravens that arrived as orphaned babies.  The aviary provides multiple perches in both sun and shade. This aviary provides a little room for the rowdy birds to stretch their wings and perch in the sun or the shade while being hand fed. Once they eat on their own, they graduate to the large 25′ x 25′ x 12′ aviary!

Ravens and crows belong to a family of birds called Corvidae.  Members of the family, which also include jays and magpies, are referred to as a group as Corvids, and are often considered some of the smartest birds in the world.  California Wildlife Center staff and volunteers often give the ravens and crows toys or hide their food in puzzles as enrichment and to teach them valuable skills they will need in the wild.

What Are You Looking At?

The many different faces of wildlife rehabilitation

Northern Mockingbird by Denys Hemen

A Northern mockingbird gives a glare to CWC rehabilitators. Photo by Denys Hemen

By Hospital Manager, Denys Hemen

Spring came with a bang this year as our nursery exploded with baby birds. California Wildlife Center is the only wildlife rehabilitation center in Los Angeles County that takes in native baby songbirds. We get in hundreds of individuals of many different species….all of which look grumpy. No matter what we do we cannot erase the look of disgust from these birds faces. We hand feed mealworms, waxworms, and crickets for 12 hours a day. Everyone gets a special vitamin supplement daily to help them grow stronger. We add natural leafy branches to the insides of their enclosures. We weigh them all every other day to make sure each bird is properly gaining weight. Still all we get are grumpy faces! It doesn’t bother us though. We just shrug it off because in the end we are all here for one thing…. to see the angry looking little birds grow into beautiful happy juveniles and take off into the sky to be free again.

California Towhee by Denys Hemen

A California towhee (above) awaits its next feeding. Photo by Denys Hemen