Burrowing Owl

Young Survivor

Written by: Maria Rakita, PHSS Intern

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Patient 21-1465 was a baby Grey Squirrel that fought to survive by her strong will and with the help of Pelican Harbor Seabird Station. Patient 1465 had fallen from her nest when she was found by a local bystander. They attempted to renest her, but sadly the renesting was not successful and she had to be brought in eight hours later. During her intake examination, she was found to be cold to the touch, slightly dehydrated, timid, had dirt in her nose, and weighed 39 grams. Patient 1465 was in dire need of help, especially since she wasn’t able to be reunited with her mother.

    After her intake examination, she was given fluids subcutaneously and oral mammal electrolytes. Fluids that are given subcutaneously are similar to the fluids given to a person through an IV. It is meant to keep the patient hydrated under the skin, hence sub(under) cutaneous(skin). In order to give fluids subcutaneously, the fluids must be calculated based on their weight, then we add a small amount of vitamin B12 to the fluids. The fluids will build up and create a bubble under the skin which will slowly be absorbed by the body. The electrolytes that were given are meant to help rehydrate the baby squirrel. We have specific refeeding guidelines for new orphaned babies. They start with mammal electrolytes and are slowly introduced to a specialized formula. We do this because the formula we give them is not exactly the same milk they get from the mom, so introducing them to our formula too quickly can cause digestive issues and dehydration. The main plan was to keep an eye on her attitude, weight, and normal physical growth. We updated her feeding plan daily to determine how much milk she will be fed and when to introduce solid food. 

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    Feeding squirrels can be extremely difficult because they are prone to aspiration, a condition in which fluid is inhaled into the lungs. When a squirrel becomes aspirated it can lead to more severe problems such as aspiration pneumonia which is why we encourage the public not to feed them. Unfortunately, patient 1465 became aspirated a couple of days after she was brought in because she was so hungry, she suckled too hard on the nipple. It could be deadly if not treated, however patient 1465 was in good hands and was given medicine right away. She got SDT (an antibiotic), as well as nebulization treatments to help clear out the lungs and prevent aspiration pneumonia. 

      Patient 1465 progressed very well with the treatments prescribed. As she grew in age, weight, and physical appearance she was able to eat what we call a soft squirrel diet and her formula. Soft squirrel diet is soft fruit and vegetables, as well as a specific biscuit that is soaked in water, so it is soft. Her weight increased and her fur looked healthy and soft. After a month of being fed formula and a soft diet, she was paired with other squirrels around her age to become wilder. We want a squirrel to become “wild” so it has a better chance of survival in the wild, so by pairing up squirrels they will be influenced by each other’s crazy and excited behavior. Since patient 1465 came in so quiet she was very calm, so pairing her up with other squirrels helped her become wilder. Patient 1465 and her group were fed a dry diet now which means they had fruit and vegetables, nuts, seeds, and a specific biscuit that is hard. Once squirrels’ teeth start to grow it is important to provide them with plenty of hard food that will prevent their teeth from overgrowing. 

   The next month, patient 1465 was moved outside into our aviaries to get used to the outdoor climate, socialize more, and hone her natural behaviors and skills.  It is important to contact your local wildlife center if you find an injured or orphaned wild animal. This way they can properly assist you in what to do. We understand that when people find animals they are just trying to help but what we want to express is that what you think may be helping the animal could actually be harming it further. Pelican Harbor Seabird Station’s clinic staff has the proper training and experience when it comes to treating and caring for South Florida's native wildlife. All in all, squirrel 21-1465 was released and is now living her best life in the wild.

A Hoot and A Half

Written by: Cynthia Verling, PHSS Intern

Imagine you are walking on a sunny day in the lovely city of Cape Coral and stumble across a burrow! You wonder, who made this carefully crafted burrow their home? Is it a mole? Is it a gopher? It’s a burrowing owl! With bodies reaching a maximal length of 9.8 inches and a wingspan of 21.6 inches, these one of a kind avians are one of the smallest owls in the State of Florida and are classified as State Threatened by the Florida Fish and Wildlife Conservation Commission (FWC)., These ground-dwelling owls create burrows and nests underground, as hinted at within their scientific name, Athene cunicularia – cunicularia meaning to mine or burrow in Latin. Unlike the usual image of owls peering down from trees in dense forests, burrowing owls live in vast open habitats, such as grasslands. Their burrows can stretch for lengths ranging from 6 to 10 feet, consisting of intricate tunnels weaving about 3 feet below the surface containing several bends and paths at the end of which a chamber can be found that harbors their nest., Some owls will use existing burrows or even pipes to build their burrows. The entrances to these humble abodes consist of mounds of dirt, grass, human trash articles, and are also covered intentionally by the owl with animal dung to attract insects which they can then eat. Their burrows not only serve to store away food in plentiful amounts during the period of incubation and brooding, but also provide an environment in which temperatures are better regulated and further aid in preventing the owls from dehydration during very hot days. Although, with increasing human developments and urbanization, habitat loss is an imminent and ongoing threat to these owls. In response, these owls begin to build burrows in urban environments, such as golf courses or even airports. Characteristic traits of adult burrowing owls include their dazzling yellow eyes, spindly long legs that allow them to get a better outlook from the ground-level, short tails, brown dorsal feathers with white spots and white ventral feathers with brown bar-shaped patches, distinct white eyebrows and throats, and characteristic round heads without the familiar ear tufts commonly seen in woodland owls., Nestlings on the other hand have cream-colored downy feathers that have less distinct speckles. Their diet consists mostly of insects but can also include other small birds, fish, rodents, and particularly in Florida, reptiles, such as snakes, frogs, and lizards, as, after all, raptors are carnivores.

The burrowing owl is arguably a perfect embodiment of the idiom “rare bird,” as it has so many unique attributes that set it apart from other birds in the family Strigidae. In addition to their peculiar small size and absent ear tufts, these owls are diurnal rather than nocturnal during the breeding season, thus showing activity during the daytime., Known to be very animated and sprightly, it is not uncommon to see these owls bobbing and bouncing up and down, while nestlings will even playfully leap at one another and prey, accruing at the same time important behavioral skills to prepare them for hunting later in life. Interestingly, nestlings also are known to imitate the rattling of a rattlesnake from within the protection of their burrows as a defense mechanism to ward off unwanted visitors, such as predators and humans., As a consequence of being the only species that perch on the ground, burrowing owls behave differently than one would expect; for example, if bothered or hunting they can be seen pushing themselves flat against the ground or running, respectively, as opposed to flying like owls usually do. Even more fascinating is that unlike other raptors, where the female is visibly larger than the male, which is termed “reverse sexual dimorphism,” female and male burrowing owls are the same size, with the latter being only a mere 3% larger – a size difference imperceptible to the naked human eye at first glance. Furthermore, male and female Burrowing Owls bear the same coloration, which is interesting as sexual dimorphism dictates that female and male conspecifics have traits that differ between them, and in many birds, this usually results in males exhibiting a visibly larger size or significantly more extravagant plumage coloration or ornamentation– traits that serve in courtship or competition for mates. Burrowing Owls pair for life, and unusual for an owl, are not solitary, but rather prefer to live in small colonies. This can be explained by the principle of group living, believed to have evolved independently in many different species. Group living confers advantages such as greater protection against predators, group defense, increased feeding efficiency, sharing of behaviors and communicating information, increased rate of reproduction due to access to potential partners, shelter, division of labor, and social thermoregulation. Burrowing Owls exhibit such social behaviors as the male and female even take turns in incubating the eggs, foraging, and caring for the offspring. Therefore, smaller species are often found living together in groups. Lastly, due to the significant amount of time they spend underground where there is less oxygenated air, they have an adaptation that confers them an increased tolerance for carbon dioxide.

These incredible avians are, however, under threat of habitat loss, degradation, and fragmentation, as well as climate change, and rodenticide poisoning, which all have long-lasting impacts on entire ecosystems. Burrowing owls fall victim to secondary rodenticide toxicosis called “bioaccumulation” when they consume rodents that have consumed rodenticide., Second-generation anticoagulant rodenticides (SGARs), e.g., brodifacoum, are slow-acting anticoagulants, which result in the rodents not dying instantly. This leads to poisoned rodents slowly becoming weak, but because they are not instantly killed, they roam about, becoming more easily caught by predators such as Burrowing Owls. Bioaccumulation, however, causes for the period the rodent is alive to allow for a buildup of toxins to a much greater lethal dose. As the owl consumes the rodent, the toxin moves through the food web from rodents (secondary consumers) to burrowing owls (tertiary consumers), running the risk of accumulating even greater lethal amounts of poison over time at a rate greater than it can be broken down, this time in the burrowing owl. Brodifacoum is according to one source, the most widely used rat poison in the United States, and has a very long half-life in animals. A study conducted from 2006 to 2010 at Tufts Wildlife Clinic at Tufts University’s Cummings School of Veterinary Medicine reported that from 161 birds, 86% had anticoagulant rodenticide residues in their liver tissues, of which 99% had brodifacoum in their liver tissues. Moreover, only 9 of these birds that tested positive exhibited clinical symptoms, demonstrating that many affected may not show visible signs of poisoning, which is critical given the concern of bioaccumulation at an ecological level. SGARs function by inhibiting the enzyme vitamin K reductase, which under normal conditions allows for the reactivation of vitamin K – a fat-soluble vitamin that plays a vital role in the coagulation cascade by producing coagulation factors I, II, VII, IX, and X in the liver and synthesizing Protein C, Protein S, and Protein Z that serve to prevent thrombosis., During the coagulation cascade, the factors produced by vitamin K are crucial to allowing the downstream activation of prothrombin to form thrombin, the latter of which ultimately stimulates the conversion of fibrinogen to fibrin, which traps platelets to form a spongy mass that hardens into a blood clot and prevents one from bleeding out. Additionally, the Cornell Wildlife Health Lab explains that animals commonly have stores of clotting factors that delay the full effect of poisoning for 3-5 days following ingestion and the hemorrhaging onset. While coagulation panels (a blood test) exist for diagnosing anticoagulant rodenticide toxicosis in domestic animals, there are currently no existing blood tests for birds to screen for rodenticide toxicosis. Burrowing owls that get a lethal dose through consuming an affected rodent face an inhumane slow death from internal or external bleeding that causes them to weaken, which may cause them to obtain injuries in the meantime, until either the hemorrhaging or other life-threatening injuries sustained while weakened eventually kill them. If rodenticide toxicosis is evident, vitamin K can be administered to act as an antidote and help restore the blood coagulation cascade to normalcy. Additionally, stomach flushing, inducing vomiting, and administering activated charcoal are all treatments that may be used to prevent additional absorption of toxin by the body. 

Raptors such as Burrowing Owls play a critical ecological role both in the wild and in urban areas. Rodenticide toxicosis in these incredible avians is not just an issue to be left to conservationists and wildlife rescue and rehabilitators, but is a public issue that must be addressed at the source to prevent further systemic damage throughout food webs, as maintaining a sustainable and biodiverse ecosystem is a necessary goal for conserving, protecting, and restoring healthy and vibrant wildlife and their habitats and by extension and directly in relation also human health, as we are all connected and a part of the planet’s ecosystem.

Sources:

Conway, Courtney J. “Burrowing Owls: Happy Urbanite or Disgruntled Tenant?” In Urban Raptors: Ecology and Conservation of Birds of Prey in Cities, edited by Boal C.W., and Dykstra C.R., Washington, DC: Island Press, 2018. 

Cornell University. “Burrowing Owl: Identification.” The Cornell Lab of Ornithology

Cornell University. “Raptors and Rat Poison.” The Cornell Lab of Ornithology

Cornell University. “Rodenticide Toxicity.” Cornell Wildlife Health Lab

Florida Fish and Wildlife Conservation Commission. “Burrowing Owl.”

Khan, Safdar A., and Mary M. Schell. “Anticoagulant Rodenticides (Warfarin and Congeners).” Merck Veterinary Manual. Last modified October, 2014.

Libre Texts. “Role of Vitamin K.” Last modified August 13, 2020.

Murray, Maureen. “Anticoagulant Rodenticide Exposure And Toxicosis In Four Species Of Birds Of Prey Presented To A Wildlife Clinic In Massachusetts,” 2006-2010. Journal of Zoo and Wildlife Medicine 42, no. 1 (2011): 88–97.

National Audubon Society. “Guide to North American Birds: Burrowing Owl.”

National Geographic. “Biomagnification and Bioaccumulation.”

National Marine Sanctuary Foundation. “Sea Wonder: Burrowing Owl.”

Owl Research Institute. “Burrowing Owl: Athene cunicularia.”

Runnells, Charles. “Cape Coral's burrowing owls: Everything you need to know about the city's famous bird.” The News-Press. February 23, 2019.  


Vallejo, David. “Animal’s social behavior: Group living.” Zoo Portraits. July 17, 2018.