Migratory birds: tireless traveler

Do you realize that some birds appear for certain time and place but suddenly, one day, dissapear again until the next year? Where do they go and why do they decide to fly though thousands of kilometres? Certainly, migration of birds is a phenomenon that has fascinated the human being from the beginning. In this post you will have an overview of the migration and discover fun and interesting facts of these wonderful birds. 

WHAT IS THE MIGRATION?

Migration is a natural phenomenon that happens in different species, but is particularly striking in birds. Requirements of essential resources (food, breeding areas,…), in several phases of their life cycle, is the main reason to start the journey to look for more favourable terms. The migration is a regular seasonal  movement that are performed by birds and coincide with the amount of a resource or different seasons, between breeding and wintering grounds.

Migration of short distance, for example when animals are moving from mountain areas at lower altitudes because of the temperature. On the other hand, migration of long distance when birds are traveling thousands of kilometres  through physical, meteorological and ecological barriers.

From Ice Age, migratory birds have evolved to fly long distances because in this way they are able to occupy different habitats and benefit from season resources in other climates. The migratory behaviour originating from an evolution because of climate changes on the Earth, and it is necessary an animal adaptation to the conditions in the new area. This behaviour was developed in species from more Northern latitudes in the Northern Hemisphere and in southern regions in the Southern Hemisphere.

WHAT TYPES OF MIGRATORY MOVEMENTS ARE THERE?

Migratory birds travel twice per year, in different seasons and times in their annual cycle. In the prenupcial (or spring) migration period birds fly from wintering to breeding areas. In the breeding areas there are enough resources to feed their offspring and safe breeding places. In the postnupcial (or winter) migration period adults and young birds fly to the wintering areas because of the weather and the high resource availability.

Group of grus in the wintering area where weather and conditions are better than en North of Europe – Photo: Manuel Gómez Calzado

These movements have concrete patterns in each species and develop the different migratory routes, but researches have discovered the routes can be variables.

So, according to the migratory pattern there are longitudinal, altitudinal or latitudinal migrations. It could be variances in migratory behaviour between individuals, including in the same species, according to several factors us age, sex or population.

MIGRATORY ROUTES

Birds use these migratory movements through specific routes, with important features (catchment of a river, mountain ranges, coast,…) and ensure favourable conditions for the journey. Also, the rest areas are used to rest and feed in long routes.

Migratory routes on the world – Photo: SEO-BirdLife

In the majority of birds from Europe and Asia, such us storks and vultures, spend the winter in the tropical Africa area, crossing their route the Arabian Peninsula and the Suez Canal. Migratory birds from the United States and Canada have their wintering areas in Mexico and Central America, and their routes depend of their area of origin: birds from east cross through the Gulf of Mexico or the Mississippi river basin; birds from west through the Rocky Mountains and Mexico Mountains, and finally, birds from Pacific used the cost or the open sea.

However, the routes can be different and depend of the distribution of birds; for example a bird species from Eurasia that pervaded North America. Their relatives used to spend the winter in Africa, so the population from North America cross Canada, the North Atlantic and Europe to spend the winter in Africa.

Researches show the routes are not so fixed us we though, and they can change according to the requirements of the species and environmental conditions over time. Also, there are fluctuations between different groups in the same species.

HOW DOES MIGRATION HAPPEN?

Human beings have always tried to answer the question ‘how is it possible birds fly so far?’. Several researches shows birds use a mix of mechanisms to migrate: the
Earth’s magnetic field, positions of the Sun, Moon and stars, polarized and ultraviolet light, recognising geographical features, reflected sound waves, taste and smell.

A research showed the migratory birds have proteins on their retina that is like a light-sensitive compass. When it is lightened with sunset light, the CPF molecule reacts and forms other compound that is sensitive to the magnitude and direction of a weak magnetic field. Two electrons rotate in opposite direction because of this chemical reaction, and the bird finds the north and south direction.

A group of proteins that birds use during the migration – Photo: http://concienciangela.blogspot.com.es/

For some birds, such us the mayority of passerine birds, migration is an innate and individual process and they have special mechanisms to find the right way. In other cases, when birds fly in group, the migratory behaviour is developed through social learning because young birds travel with adults. Birds born of parents with different migratory routes used to choose a middle migratory route.

DISCOVERING SOME CURIOUS FACTS

The bird that travel father is the Arctic tern (Sterna paradisaea) from the Arctic, its breeding area in summer, to Antarctic to find food in winter. This distance is about 80000 km per year, and this species has developed the ability to sleep with a hemisphere off and another on flying directly.

Arctic stern (Sterna parasidaea) and its migration – Photo: Birdlife

 

 

 

 

 

 

 

 

 

In a research about Alpine swift (Tachymarptis melba), it was showed that this species can stand on the air for 6 months in their migration to Africa. The most interesting is that all vital processes are being on the air.

The migratory bird that flies higher is the common crane (Grus grus) and they can fly over the Himalaya mountain each year carried by the thermal currents. Breeding areas of this species are in the north of Europe and Centre and Northwest of Asia, also there are some groups in southeastern Europe and close to the Caspian and Black Seas. The wintering areas are in Spain, Portugal, north and east of Africa, south of France and south Asia.

REFERENCES

• “Birds Migratory flyways influence the phylogeography of the invasive brine shrimp Artemia frasciscana in its native American range” – Joaquín Muñoz, Franciasco Amat, Andy J. Green, Jordi Figuerola and Africa Gómez
• Effect of climate on the migration behavior of the common buzzard Buteo buteo – Martin, Beatriz; Onrubia, Alejandro; Ferrer, Miguel – 2014, Climate Research 60: 187 – 197 (2014)
• Regional Forest Fragmentation and the Nesting Success of Migratory Birds – Robinson, Scott K.; Thompson III, Frank R.; Donovan, Therese M.; Whitehead, Donald R.; Faaborg, John; – Scientific Journal (JRNL) – 1995

 

• Cover photo: A group of cranes traveling to their wintering areas – Jacinto Alduan Palacín – http://jacintoalduan.blogspot.com.es/

 

 

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.

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.

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.

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

5 experiences in a wildlife rescue center

If you’re a former, present or future biology student this interests you. One of the most rewarding work experiences I ever had was working in a wildlife rescue center. Actually, I worked as a technical assistant veterinary, but allowed me to know how a center like this (led by a biologist) works and have direct contact with wildlife. These are just 5 experiences and lessons learned from that adventure.

WHAT IS A WILDLIFE RECOVERY CENTER?

It is a center where sick or injured wild animals are welcome where they have veterinary care and food until they are able to fend for themselves. Then they are released into the wild. This centers are of great importance for the conservation of the species, especially those that are endangered or vulnerable. The contact with animals should be the minimum to avoid humanizing them and not change their behavior so they can survive once reintroduced in nature.

Some centers also breed in captivity threatened species, such as the Hermann’s tortoise (Testudo hermanni) to try to recover wild populations introducing the offspring in nature.

Eagle flying in the Wildlife recovery center “El Valle”, Murcia. Photo taken from Murcia enclave environmental

Unfortunately, some animals are unrecoverable due to his injuries or behavior, so in the center they lived some birds of prey such as the goshawk (Accipiter gentilis) to be an example in environmental education and awareness.

If you find an injured animal, NEVER try to keep, treat or feed it: probably you’ll cause more injuries. Always call one of these centers or local authorities. They have the facilities and appropriate knowledge to treat these animals.

1. CLEAN, CLEAN AND…  MORE CLEANING

The first information I got when I entered the center was: “80% of the time of this work is to clean the animal facilities. But the remaining 20% ​​is  worth rewarding. “

The director was right. It is a job where you’ll get dirty, and if you’re a little apprehensive, it is not for you or you’ll need to get used (and believe me, you get used to almost everything , cleaning was not the hardest thing I faced). But see how it goes ahead an animal that you have taken care, is priceless.

2. THE WONDER OF WORKING IN THE MIDDLE OF NATURE

The dream of many biologists is working in direct contact with nature. These centers are usually in it, which gives the opportunity to work outdoors, away from the stress and pollution of the city. Sometimes it rains, makes a blazing sun or cold temperatures will freeze your hands and cut your skin. But the good times are terribly comforting. Many of us prefer put up with occasionally adverse weather conditions  rather than being locked in a windowless office for 8 or more hours

In my case we also had a pair of attached facilities outside the center and had to go every day strolling through the woods, with the added appeal and adrenaline (especially if you met a wild boar) to see animals and plants in their habitat.

Natural park of Montseny. Photo by Mireia Querol

The field work was completed by the laboratory and treatment room: analysis of feces, blood, muscle… to detect the presence of parasites in new animals, future reintroduced ones and dead ones: autopsies allow to have a record of possible diseases and epidemics of local fauna.

3. GIVE LIFE… BUT ALSO QUIT LIFE

In addition to maintain proper hygienic conditions, the main occupation that I had was to feed the animals. At that time there were mammals like hedgehogs, badgers or foxes which we fed with fodder and supplements such as worms.

For raptors, one of the most frequent tenants, the diet was based mainly in chicks and mice. The chicks were bought frozen, you just had to plan the thawing and leave them on their premises. In one case I had to hand feed one tawny owl (Otus scops) with a broken wing, so the contact with the animal was inevitable. And feeding a nocturnal bird of prey, althought it was a small one, is complicated task the first time!

Tawny Owl (Otus scops). Photo by Mario Cea

The mice instead were kept alive. By ethics and risk the animal was injured, we had to kill them with the least possible suffering before serving them as food. To learn the technique and do it properly, creates a sense of contradiction, so it’s better to focus on the animal you’re trying to save as a peregrine falcon (Falco peregrinus), a viper (Vipera Aspis), a tawny owl (Strix aluco), kestrels (Falco tinnunculus), a hawk (Accipiter gentilis)… For herbivores, such Hermann’s tortoises (Testudo hermanni), was much easier to prepare their food. And the nicest thing, to feed a baby squirrel (Sciurus vulgaris).

Nurse feeding a baby squirrel. Photo by Ezequiel Becerra

The hardest moment is where you have to euthanize an animal. Unfortunately, some animals are seriously injured and you can not do anything to save them. In other cases, if it is not priority species (such as gulls, pigeons, invasive species…) lack of resources and/or legislation euthanasia is the only solution left. First the animal anesthetized to avoid unnecessary suffering, and then euthanized with a syringe directly into the heart to make it as fast as possible. Find the heart with a stethoscope and have to check it has stopped is one of the most harrowing experiences that I had to live there.

So death is also present in these centers. Causes frustration and sadness see dying an animal you are trying to get ahead, or having to euthanize it to avoid suffering, but it is one of the difficulties it has to be faced.

4. HUMANS, THE MAIN REASON OF INCOME OF WOUNDED ANIMALS

The animals arrived to the center through forest rangers, with which you have constant communication, associations or other institutions or individuals. On occasions we moved because it was impossible to move the animal: a huge wild boar (Sus scrofa) hit by a train. The collisions are a leading cause of death of wild animals. The situation could not be more daunting: rain, the animal on the roadside in a pool of his own blood and mud. Were difficult times as we had to apply higher euthanasia doses than normal because he clung to life, besides having to ensure our own security. Finally, for all of us the suffering ended. Dirty and sad, we get on the jeep back to the center.

Fox hit by a car. Photo taken from 20 minutos

The possession of wild animals as pets causes accidents by negligence or ignorance of their owners: was the case of an eagle which it had cut its primary feathers so he could not fly when it wasn’t a harmless chick anymore. He had to undergo surgery and expect to grow new feathers and learn to fly again.

Pets themselves also causes serious injuries: for example tortoises, iguanas bitten by dogs…

The traps, poisoning and direct shots of hunters , even on protected species like raptors, is another cause of having animals in these centers. Birds also face hazards such as power lines, pylons, wind turbines, wired fences … death traps for many of them.

Dead eagle because shot pellets. Photo taken from Quo

There were few cases where the causes of admission to the center were natural or impossible to determine. In fact, I do not remember any.

5. THAT FEELING WATCHING A RECOVERED ANIMAL FLYING TO FREEDOM

The most wonderful moment is that one in which the animal is ready to return to nature. Planning how and where, taking the journey to the place, checking the surroundings (and if lucky, with the sighting of other species) the moment you open the cage. .. and you see these two kestrels that you have been feeding for months, eager to rise into the sky, you with binoculars in your hand observing them away into the vastness to become tiny black dots… and disappear. I’ve never seen more clearly a metaphor of what freedom is. That feeling, like love, can not be explained.

Maybe it is love, after all

Cover photo: Mireia Querol. Griffon vulture (Gyps fulvus) in flight over the Foz of Lumbier (Navarra, 2007).

* The photos of this post do not belong to the animal rescue center, they are used as an example of the species listed in the post

Bearded vulture: conservation of a unique bird

Last month a bearded vulture was born for the first time in Spain of parents bred in captivity and reintroduced into the wild. The bearded vulture is the only bird in the world that feeds almost exclusively on bones. Like the Iberian lynx, it is one of the emblematic animals of the Iberian Peninsula and it is endangered, so it is subject to various conservation and reintroduction programs. In this article, we encourage you to find out more about the bearded vulture and the spanish conservation projects.

DESCRIPTION

The bearded vulture (Gypaetus barbatus) is a diurnal bird of prey popularly included in what is called vultures, scavenger and ghoul birds (they feed on dead animals). However, the bearded vulture is quite different from other vultures:

Adult bearded vulture (Gypaetus barbatus). (Photo by Jose Luis Ojeda)

 

• It is so highly specialized that 85% of their diet are bones (osteophague) of dead mammals such as wild ungulates (chamois) and domestic cattle (goats, sheep). It can swallow bones up to 25 cm, and if they are too large catches them, rises them to 20-40 m and crashes bones against the rocks into smaller pieces that can swallow. It also uses the same technique to break tortoise shells.

• It is very large, with a wingspan up to 2.8 meters and a weitgh up to 7 kg.

• In general it isn’t noisy: it just whistles if it is excited or during the mating season.

• It hasn’t the typical plucked vulture head. Vultures have a few or no feathers on their heads to maintain an optimum hygiene after putting their head in dead animals. Due to its peculiar diet, the bearded vulture has more feathers on head and neck, with its characteristic “beard” below the peak.

• The plumage is the same for both sexes but changes with age. The typical reddish and yellowish adults plumage is due to their habit of bathing in mud rich in iron oxides, otherwise they will had a white breast.

Plumage phases of the bearded vulture, Adam and Llopis (2003). (Image by © X. Parellada.)

In this video (5 minutes, catalan) you can see bearded vultures in flight, breaking bones, engulfing them, raising a chick in the nest and bathing in mud.

REPRODUCTION

Bearded vultures nests on ledges and natural rock caves in the mountainous and rugged areas where they live. They have stable partner for life from age 7 and the reproductive cycle has different stages:

• Pre-laying (September to November): nest building (covering it with branches, wool, feathers, bones …), defense of territory and sexual activity.
• Incubation (December-February): they lay one or two eggs with a time difference of 6 days. Both sexes participate in the incubation for 53 days.
• Nurturing (March-August): the largest chick kills his brother (fraticidal violence) to ensure survival. Parents provide food and when the chick leaves the nest (June-July), learn from them to find and prepare food until their emancipation.
• Emancipation (January): displacement (thousands of kilometers) and dating back to the land where it was born to breed (philopatric instinct).

Tracking of natural nests with cameras. (Photo: Foundation for the Conservation of the Bearded Vulture)

DISTRIBUTION

Subspecies Gypaetus barbatus meridonalis is distributed by the South and East Africa, while Gypaetus barbatus barbatus by North Africa and parts of Eurasia (see map).

In the Iberian Peninsula is found naturally only in the Pyrenees (Catalonia, Aragon and Navarra). Spain is the European country with more breeding couples registered (about 130, 2014 data).

Bearded vulture distribution. In red, areas in which has been reintroduced . (Image by Mario, Wikimedia).

THREATS

Bearded vulture populations are declining. It is ranked globally as“near threatened” in the IUCN Red List and “endangered” in the Spanish Catalogue of Endangered Species. Current threats they face are:

• Death by poisoning (illegal baits, poisoned animal consumption, consumption of remains of lead hunting ammunition –plumbism–).
• Death by electrocution or collisions with power lines and wind turbines of wind farms.
• Poaching
• Habitat loss and decreasing of reproductive efficiency because of the humanization of the medium (urbanisation, adventure sports …)
• Reduction of food (cattle in stables, obligation to bury the corpses …)

Bearded vulture dead by poisoning. (Photo: DARPAMN)

CONSERVATION IN SPAIN

Due to the limited distribution of populations, their low number and difficulty to colonize new territories, in 2014 thirteen autonomous communities signed a protocol for the recovery of vultures in Spain. The most prominent action of this protocol is to strengthen the National Strategy for the Conservation of the Bearded Vulture in Spain (started in 2000) and the Programme Captive Breeding (2001), with actions such as the revaluation of rural areas, supplementary feeding and support for traditional farming practices. This strategy also involves the reintroduction in historic areas where the bearded vulture has been extinguished:

• Reintroduction in Picos de Europa: after 70 years extinct, in 2006 two individuals were reintroduced in the National Park, managed by the Foundation for the Conservation of the Bearded Vulture, which currently continues to develop projects for the recovery of vultures in Aragón.
• Reintroduction in the National Park of Cazorla, Segura and Las Villas: in this area of Jaen no breeding was registered since the 80s of last century. The Gypaetus Foundation manages the Captive Breeding Center of Cazorla and the Life Project 04NAT/ES/000056 for the reintroduction of bearded vultures in Andalucia by hacking techniques.
  

WHAT IS HACKING?

Hacking or rural upbringing is a technique that involves the release of captive-bred animals in an area that the bird assimilates as its birthplace. If successful, the bearded vulture returns to settle and breed. This technique did not has a conservationist origin, since it was developed by falconers in the Medieval Age. Falconry (hunting with birds of prey) are also currently used for wildlife control at airports or cities.

In falconry hacking consists in lefting in an elevated cage chicks that can feed by themselves. Falconer feeds them without being seen. After a few days they open the cage, using it as a basis for learning to fly. They are still feeding them until they learn to hunt by themselves and leave the cage. The young ones connect the cage as its birthplace so it will always return.

Feeding a chick with a decoy to avoid human contact and make its life possible in the wild. (Photo: Foundation for the Conservation of the Bearded Vulture)

The center managed by the Gypaetus Foundation is based on the natural breeding, with minimal human intervention. Parents raise and feed their young from the second week of hatching. To monitor the nests a video surveillance system is used.

Since 2006, 31 bearded vultures have been released from captive breeding and each one is tracked by GPS transmitters. Currently 15 individuals are still sending signals (9 were killed and 7 stopped working). As said in the introduction, the good news is that last month was born the first chick result of released individuals (Tono and Blimunda) by hacking technique.

For more information, check out this documentary (in spanish) about the bearded vulture and its conservation (El bosque protector. Fauna amenazada, El Quebrantahuesos, 29 minutes).

REFERENCES

• Fundación Gypaetus
• Fundación para la Conservación del Quebrantahuesos
• Grup d’Estudi i Protecció del trencalòs
• Enciclopedia virtual de los vertebrados españoles (MNCN)
• Ministerio de Agricultura, Alimentación y Medio Ambiente
• La cetrería y conservación de rapaces
• Cover image by jayhem