Arxiu d'etiquetes: owl

Flying again: exercise for convalescing raptors

When an animal is admitted to a Wildlife Rehabilitation Center, it starts a long process to survey and be released in nature. In this article we are going to discover one of the most exciting and difficult stage in raptor rehabilitation: the recovery of flight capacity. Finally, I will tell you some tips for attending injured birds.

WHAT IS A WILDLIFE REHABILITATION CENTER?

For all species the survival is a challenge. To the natural tests we have to add the threats of our life: poison, shots, electrocution, collisions are the daily admissions’ reasons in a wildlife rehabilitation center.

The Wildlife Rehabilitation Centers have the purpose to rehabilitate incapacitated wild species to release in the nature in the best conditions and secure its adaptation and survival.

Every time, when a wild animal is rescued and moved to the Rehabilitation Center a cooperation team word for days, months and years starts with an single purpose: the animal’s freedom.

The first step for an animal’s admission is the exploration to determinate its health and to obtain a diagnosis. Also, the species’ information is necessary (species’ name, age, sex, biometric data). According to its health’s gravity, the veterinary will choose to keep it in the ICU (Intensive Care Unit) for a strict control and treatment, move to a environment place or flight (for birds), or even directly the freedom.

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Owl (Bubo bubo) with injures in right wing – http://www.verkami.com

Specific food, adequate hydration and handling according to the physiological and ethological features are important for the process, since the animal is rescued until its release.

RECOVERY OF INJURIES AND DECREASE OF THE FLIGHT CAPACITY

An optimum flight capacity is essential for birds, but in raptors is more important because of hunting require different types of flights according their vital strategy (the best way to hunt  is an increase in quantities and quality of food with the lowest possible energy cost). Some birds have to fly in reduced spaces and speed is cruel to hunt, such us forest species (goshawk and sparrowhawk), and other raptors can use the termal air currents until they reach the sufficient altitude to move effortlessly (vultures). These characteristics must be borne in mind when planning rehabilitation training.

Regarding raptors, their recovery of injuries involve periods of inactivity that could decrease the physical condition creating muscle atrophy and circulatory disorders. However, this inactivity period is necessary in most circumstances and veterinarians provision an adequate food and vitamin supplements maintaining a body condition to facilitate the recovery. So, when injuries are recovered, raptors will need exercises before they are released.

AFTER THE REHABILITATION… TO THE GYM!

Different techniques, with the purpose to increase slowly the animals’ muscular mass and recovery its flight’s skills, are used for the raptors’ rehabilitation.

  • Common facilities to rehabilitation: it is common to use them because it is only necessary to have suitable and big facilities with perches in different distances and height which help the bird’s flight. Another benefit is that many animals can stay in the same facility reducing the stress of the human contact and improving their social behavior. The problem is that the flights are not under control, the rehabilitation is slow, and the bird makes only minimum flights to reach the food place.

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Vultures (Gyps fulvus) in common facilities to fly – Photo: Patricia, http://www.diariodeburgos.

  • Rehabilitation using guarantor: this method can be used for large birds, which would need big facilities, and is based to exercise in open field with guarantors (large ropes with ballast at one end to avoid escape of birds, the other end is used to hold their tarsus with a leather This exercise is more efficient, testing about flight capacity and a monitoring process can be obtained. Disadvantage is greater stress because of transport to training place and handling during the exercise. It is therefore essential to carry out a risk analysis to assess the cost (direct handling, stress,…) and benefit (extent of their flying range) taken into account the individual behavior.

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Bonelli’s Eagle (Aquila fasciata) in rehabilitation flying with guarantor – http://www.grefa.org

  • Facilities to rehabilitation in oval design: First circular facilities to rehabilitation were used in the United Arab Emirates due to the long tradition of falconry (it is a hunting in which man makes use of previously trained birds of prey). The facility is formed by a corridor to fly in the entire perimeter, and resting boxes where birds are housed.  This corridor is divided with moved curtains to lead them inside the boxes. In this way birds can fly continuously. Also, it is possible an indirect handling during the process: entrance and exit through manual doors and curtains to block the flight, and stress will be lower than in direct handling.  In this case, the process could be monitoring, the exercises will be twice a week firstly, and later they will be increased until all days with a time and repetition increment.

Exercises and method will be selected according to the species and their injuries. It is very interested to alternate them with other steps such us the use of pieces of meat adhering that it obliges them to work specific muscles on neck and pelvic.

WHAT WE HAVE TO DO IF WE FIND A WOUNDED BIRD?

If we find a wounded bird, we have to touch them with care, otherwise it is dangerous for us and for the bird because we could increase its wounds.

There are some recommendations:

  • Be sure that animal needs your help because sometimes bird chicks are helped thinking they are abandoned but it is wrong.
  • Use a blanket and take it fast to avoid more wounds. If we close its eyes the birds are more relax although be careful with the claws and the beak.
  • Move it inside a carton box with air holes and leave it in a quiet place.
  • Phone to the closest rehabilitation center, in order to collect the bird as soon as possible and give you the best advices.
  • Do not force it to drink or eat because it could be bad to get worse.
  • Don’t try to treat it because a specialize veterinary has to examine it.

REFERENCES

  • Mauro Hernandez Segovia, ” Birds of Prey Rehabilitation and Conservation : Veterinary Aspects ” . Ardeola 39 ( 2) , 1992 , 49-64.
  • Gustavo Aprile and Claudio Bertonatti , “Manual on Wildlife Rehabilitation ” . Argentina Wildlife Foundation .
  • Patricia Contreras Coppelia Ovalle , Maria José Ubilla Carvajal, “Evaluation of the Animal Welfare raptors in rehabilitation” . Faculty of Ecology and Natural Resources, University Andres Bello.
  • Patrick Reding. “Exercise for convalescing Raptors ” . The Raptor Center, University of Minnesota.
  • Main photo: Releasing barn owl (Tyto alba) – http://www.martioda.org

Sara de la Rosa Ruiz

Nocturnal birds of prey: the barn owl, legends and myths

Nocturnal birds of prey have suffered since a long time ago an unfair bad reputation that has led them in some cases to be persecuted and hated. What are these superstitions? Which is their conservation state? What can you do for them? In this article you will discover owls and the barn owl, Tyto albaand the legends associated with them.

GENERAL CHARACTERISTICS OF NOCTURNAL BIRDS OF PREY

As its name suggests, most nocturnal birds of prey (owls, owls, tawny owls) have nocturnal or crepuscular habits. They are carnivorous, with beaks and claws (two toes forward and two backward) adapted to tear flesh from their prey (small mammals, birds, reptiles, large insects ).

HEARING

Owls usually have a rounded shape and apparent large head, with the face feathers forming the so-called facial disk. The facial disc serves as a dish heading sounds towards the ears. The opening of the ear is large, with a fold of skin (preaural halda), which functions as a pinna and is movable as in some mammals.

Oído de lechuza norteña (Aegolius acadicus). (Foto tomada de Jim McCormac).
Norther saw whet owl ear (Aegolius acadicus). (Photo by Jim McCormac).

The position of each ear is asymmetric in some species (one is higher than the other), so some of them -like the barn owl- can locate prey in complete darkness: an ear perceives sound before the other, so their  brain can calculate the exact place where prey is (directional hearing).

Boreal owl skull, cráneo de mochuelo boreal
Boreal owl skull (Aegolius funereus) where can be seen the asymmetric hearing openings and sclerotic eye rings. (Photo taken of Jim Williams)

EYESIGHT

Owl’s vision is highly developed. Eyes, unlike most birds, are in front position, which allows a perfect estimation of depth and three-dimensional vision. On the other hand, eyes are tubular (not spherical like ours) due to the large size of the cornea and lens, which prevents owls from moving them within their sockets. Also they have a protective bone plate around the eyes (sclerotic rings) that also impede movement. To solve this problem, they are able to turn his head 270 degrees. It can be considered that they see in black and white (they best perceive changes in light rather than colors), the pupil dilates a lot in bad light conditions (iris is hidden by dilated pupil) and they are the only birds in which the eyelid closes up to below. They also have a transparent lid” that moistens and protects the eye, called the nictitating membrane.

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Binocular vison of a nocturnal bird of prey. Humans have a field vision of 180 degrees, 140 of them binocular). (Image by The Owl Pages)

PLUMAGE

Owls, unlike diurnal birds of prey, have a special flight feathers structure, fringed at the top surface and contours. The friction between them and the air is damped, achieving a spectacular silent flight undetectable by preys.

Pluma de lechuza común y autillo, donde se observan las barbicelas. (Foto tomada de Pedro Montoya).
Barn owl feather (Tyto alba) and european scops owl (Otus scops), (Image taken of Pedro Montoya).

THE BARN OWL

The barn owl (Tyto alba), is unmistakable: it has a very well defined and heart-shaped facial disk. The back is gray with golden spots and fine black and white dots.

DISTRIBUTION AND BEHAVIOUR

The barn owl lives all over the world (except Antarctica, north Europe and most Asia) and don’t build a nest, but lays eggs in tree holes, holes in the rock or human buildings (barns, attics, farmhouses, castles, churches ).

Why the barn owl has this negative reputation that caused their persecution in many parts of the world and in Spain? Causes are diverse, all fed by human fear:

  • They can nest in abandoned or sacred locations as churches (some with their own cemetery).
  • Nocturnal habits
  • They are sendentary, they can stay in the same hunting ground for years until food is scarce.
  • Ghostly appearance due to their colors and smooth and silent flight.
  • By their vocalizations (they have 17 different ones) like human screams and peculiar snorts. Listen to some owls making a defense vocalization in the following video:

THE BARN OWL IN THE POPULAR CULTURE. BELIEFS, SUPERSTITIONS, MYTHS AND LEGENDS

In the Iberian Peninsula was believed that owls drank the oil of the lamps in churches, leaving the Saints in the dark (when the real thieves were sacristans). By landing on lamps or touching them and pouring the oil, it was believed that owls hated light, like evil spirits. In spanish and catalan there are sayings that refer to this myth. They were hunted, killed and hanged above the doors of churches and barns to ward off fire and lightning.

The vocalizations of barn owls are also interpreted as announcements of death, and there is a belief (without basis) that if someone hear an owl for several nights (something not difficult given their sedentary habits) a person suddenly will lose life.

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Barn owl (Tyto Alba). (Photo by Kerkuil André).

In other cultures there are also negative legends about owls: in Africa that are sent by sorcerers to kill people or evil demons announcing disasters, in the Argentine pampas that they are sisters of the devil; in Sicily, death or illness for all these reasons they have been killed and tortured.

However, they can also be a good sign (such as guardians of women who die in Australia), but the best known case is the representation of Athena, Greek goddess of wisdom. Currently still appears as a symbol of many institutions and in Greek euro coins.

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Greek euro. (Resource: RTVE)

CURRENT STATUS AND THREATS

Nowadays the barn owl is in a state of decline and with an uncertain future due to changes introduced by humans in rural areas, such as changes in cultivation or use of pesticides and rodenticides, which kill their prey (mice) or indirectly birds themselves. The works and renovations of buildings where they used to nest also interfere with reproduction. They also suffer accidents due to the towers and power lines and are often hit by cars. Canary subspecies (Tyto alba gracilirostris) is disappearing due its habitat fragmentation and the low number of individuals in their populations.

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Barn owl in a barbed wire. (Photo by PacoT).

It is listed as Endangered in the Red Book of Birds of Spain and included in the National Catalogue of Endangered Species in the category “Special interest“.

WHAT CAN YOU DO FOR OWLS?

Try to find out about these magnificent birds and make them known to your immediate surrounding, banishing misconceptions, especially if you live near their nesting and feeding areas. If you own crops, try to minimize the use of pesticides: a pair of barn owls hunt in average about 2,000 mice a year, being therefore even beneficial to humans.

If you find an owl or wounded bird, you have to pick it carefully (using a towel or a jacket) to avoid hurt it or being hurt, and leave it in a dark, quiet place inside a box pierced so it can breathe. Do not feed it. Then contact a wildlife recovery centre.

REFERENCES

If you enjoyed this article, please share it on social networks to spread it. The aim of the blog, after all, is to spread science and reach as many people as possible. Feel free to share your experience with birds of prey in the comments below. ¿Do you know someone who still believe in this owl legends?

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