FALCONIFORMES
(Diurnal Birds of Prey) - Management Guidelines for the Welfare of Zoo Animals |
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SECTION 2: Management in Captivity
2.4 Breeding
Some raptors are aggressive when in breeding condition. Aviaries should be entered with great care and feeding done carefully if pairs are showing territorial or breeding behavior.
With most birds of prey the female will stop going to collect her own food and will allow the male access to food first. She may call to him for food, she may chase him begging for food, and she may, if he is unresponsive, take food from him whether he wishes it or not. This is normally the stage when pair bonds can be seen to form. If males are not giving the responses that the females need then she may turn on the male and start chasing him, terrorising him, or even injure or kill him. If a male is showing signs of fear, injury or unacceptable levels of stress he should be removed without delay. Although generally, because of her larger size the female usually is the more aggressive of the two, it does not always follow that the female is dominant, sometimes she can be the one showing signs of stress and be in need of removal. In these cases a reasonable amount of knowledge and experience in dealing with breeding birds is needed to find out which of the pair is perhaps not suitable for breeding, or if the problem is just that the particular pair are not compatible.
Aggression towards intruders in the enclosures can continue until young birds are fledged.
Food passing, nest building, copulation, calling, all of these are a fair indication that breeding attempts may be made. Mating can occur at anytime, it may be very obvious to the onlooker, it may never be seen, even by those monitoring the enclosures. There is little that can be done to encourage mating except putting the birds in the right surroundings and aiming for compatibility. Many birds will breed very readily whilst some individuals may never breed in captivity.
If nest building is seen, the adding of small amounts of new nest material, fresh greenery, and dry grass towards the end of nest building may help to encourage interest. The material should be placed in the enclosure with the minimum of disturbance.
Feeding regimes can be changed to smaller amounts given more often, thus allowing mates more opportunities for feeding the females.
Higher quality food can be used prior to the breeding season to stimulate breeding activity.
In the wild state falconiformes breed at greatly differing times of the year depending on the species, food availability, altitude and weather conditions. The same occurs in the captive state, with different species coming into breeding condition at unexpected times of the year. Bateleur Eagles can be very early, laying in December or even earlier. Monitoring of paired birds should continue throughout the year until breeding seasons are established.
Diurnal birds of prey mature at various differing ages, some such as the kestrels will lay in their first year, others such as the large eagles or vultures can take up to seven years or more to reach breeding age. Placing younger birds in with older birds can bring younger birds to breeding condition earlier than if young birds are paired together. The same procedure works putting experienced breeders in with less experienced birds.
2.4.2 Egg Laying and Incubation
Eggs
As we are dealing with all the Falconiformes, egg sizes and incubation periods are not discussed here. There are many good, up to date reference books that give this information. All the falcons lay brown speckled eggs, the caracaras being closely related do the same. The rest lay eggs of varying colours of blotched white, buff, or greenish blue. The colour tends to be paler to non existent as each subsequent egg is laid. It is not unusual for the last egg in larger clutches of falcons eggs to be almost white.
Much information is needed on egg measurements. These data can easily, and sometimes can only, be collected by those in charge of captive collections.
Most birds of prey lay an egg every other day, although larger birds such as eagle can have a longer gap between eggs. There are individual birds that do not conform and will lay with varying intervals between eggs. One problem to be watched for is egg lethargy in the females. Often females will look sick or ill just prior to laying eggs. This can lead to difficulties as on occasion the female is actually ill rather than in egg lethargy. So care should be taken at this time to ensure that egg laying females are not suffering from infection, or egg binding. If females are sitting for an unusual period on the ground, rather than perched or on the nest area, catching up and checking them should be a matter of course. Handling of females that might be due to lay imminently or are suffering from being egg bound should be undertaken with extreme care. Sudden bouts of cold weather can cause egg binding, particularly in enclosures facing into chill winds.
Keepers should start to monitor nest sites some time before egg laying occurs. This habituates the pair to keepers near the next site and should also give the date of first lay. As many of the falconiformes do not incubate from the first egg, unless the nest site is checked daily laying may not be noticed straight away.
Incubation
Natural incubation, egg manipulation
Established, experienced pairs of birds are perfectly capable of incubating, hatching and rearing without assistance. However young or inexperienced pairs may need some assistance in the first few seasons. With endangered or valuable species it is not advisable to leave the whole process to inexperienced parents as many things can go wrong.
Some birds are naturally clumsy with eggs, once a pair shows signs of breaking eggs examine the nest area carefully. Remaining eggs should be removed and if a second clutch is not required, dummy eggs can be substituted for the parent birds to continue incubating. Turned wooden eggs make excellent dummies.
If allowing birds to achieve the whole breeding cycle unaided, eggs should at least be checked for fertility after the first ten days of incubation.
Egg retrieval, candling, egg returning
Thin rubber gloves should be worn for handling eggs to avoid contamination. Two people should be present when eggs are removed. One person, with a net should gently fend off, or remove from the nest the incubating female. The female will tend to be the more aggressive bird during incubation, although that is not always the case. Care should be taken to make sure that in defending the nest, the female does not damage her own eggs. A net slid under her and either containing her, or pushing her off the nesting area is the best method. Both keepers should wear a good quality falconry glove to protect themselves. The second person, guarded by the first, should then carefully remove the eggs into a softly lined, secure and clean container, making sure that the eggs are safe. If the candling of the eggs is going to take more than a few minutes, then dummy eggs can be left in the nest, if not, returning the eggs quickly will be sufficient. Returning eggs should be done in the same manner, with two people, one to concentrate on the birds, one to manage the eggs. It is not advisable to remove eggs at night as birds may not return to incubate. Once eggs have been returned the enclosure should be left well alone to give the birds time to settle. This process is best achieved with the absence of the general public and well before dark.
Most good commercial egg candlers will give out enough light to candle all but the densest of raptor eggs. An ultra violet lamp is not necessary. Keepers should gain experience in candling eggs by learning on chicken eggs before testing the eggs of endangered species. Gentle handling of eggs is the key as rough handling can cause internal damage to the attached embryo.
If eggs are fertile and the pair is to be allowed to hatch them naturally then the clutch should be returned to the pair as soon as possible in the manner described above. If the eggs are clear then it is probably best to try and recycle the birds thus giving a second chance in the same breeding season. If so, and dummy eggs have been placed with the female during egg candling, these will have to be removed, leaving the birds with no eggs, which should, in most cases stimulate second attempts at breeding.
Most of the small to medium sized species of falconiformes will recycle at two to three weeks after the eggs have been removed. The larger species, such as the eagles don’t normally lay until a month has elapsed, sometimes even longer. Some birds may not recycle, but if the first clutch of eggs was clear, nothing is lost.
If recycling is required, the eggs should not be left with the parents for much longer than 14 days before removing or candling as once the bird is too far into incubation the desire to replace a lost clutch is past.
If clutches are found to be fertile, but the pair of birds has never reared, it is probably advisable to artificially incubate the eggs, or let broody hens do part of it. Do not let broody hens hatch eggs as they are liable to kill the young. Once hatched, young can then be hand reared for a few days before returning to the parents. A slightly older, stronger and more experienced chick is easier for the inexperienced parent bird to manage. Alternatively, if young from a suitable, less vital species are available, they can be used as foster young to see how the adults cope. If coping well the correct youngster can be substituted or even added to the clutch, depending on the species.
Breeding birds must be left on dummy eggs if young are to be returned, but double clutching is not required. Falconiformes will not accept young if they have not been sitting on eggs of some description.
Many of the eagle species suffer from cainism in the nest with the first hatched young killing the second hatched. Careful management can avoid these unnecessary deaths. By removing the second (and third if there is one) egg after two weeks of natural incubation and hatching artificially, deaths are avoided. The young can then be switched at five day intervals so that both are getting natural rearing as well as hand rearing, until the danger point is past (usually at about two and a half weeks old) and all the young can complete the rearing with their own natural parents.
If double clutching is required to produce more young of endangered species, it is advisable to have spare pairs of birds to act as foster parents. The clutches will be at least two weeks apart at hatching and the age difference is too great to allow all young from both clutches in the same nest at the same time.
During natural incubation nests should be monitored daily to check incubating birds are well and the eggs are not broken. A moment of listening may tell the keeper when young have hatched as they can sometimes be heard calling. It may be necessary to have two people approach the nest site and leave one silently there while the other retreats again. This may give the chance to see the eggs, but some birds are very loath to leave the nest. Checking at feeding times may help.
As all pairs of birds are different, common sense should be used to access each pair and decide on the best course of breeding management.
Without doubt raptor eggs have a higher percentage hatch if the eggs have some natural incubation in the first week to ten days. This does not necessarily have to be by the parent bird. Well managed broody hens will successfully incubate all but the smallest species of eggs. The hens must be kept in clean dry conditions and be used to being handled during incubation.
Egg storage
Fresh eggs that have received no incubation can be stored for short periods. However unless absolutely necessary this practise is not advised. Egg hatchability will decline after a few days. It is recommended that raptor eggs be stored only if proper storage conditions are available and then for no longer than five days. Eggs should be kept in a dry stable room, commercial chickens eggs are stored at 60.f-15.c at a relative humidity of 75 - 80%. The Peregrine Fund have had good success storing eggs for short periods with their large end uppermost and turn them through 90 degrees at least twice daily.
Artificial Incubation
Incubators
There are many different commercial incubators on the market. However the make does not really matter as long as the keepers in charge of incubators are completely at home with the make used and as long as the instruments used to measure the temperature and humidity are accurate. It is probably best to stick to one manufacturer rather than having several different types as repairs are easier and so are comparisons.
For the serious breeder at least two and preferably three incubators should be running during the breeding season. One for incubating, one for actual hatching and one to cover for mechanical break down, or disinfecting. If dealing with a large variety of species different incubators may be required to deal with the widely differing egg sizes.
Incubators and the room containing them should be well sterilised and cleaned prior to the breeding season. Incubators should be turned on at least four days before required to hold eggs. They take at least 24 hours to stabilise at the right temperature and humidity. Thermometers should be checked by placing them in ice to bring them right down and then putting them together in hand warm water and then making sure they all read the same temperature. Hygrometers, or other methods of assessing humidity should also be cleaned and checked.
Water containers and any other equipment used in incubators should be sterilised.
This cleaning process should be repeated at regular intervals during the breeding season. However if fumigation is to be the method used, viable eggs should be removed from the incubation room while any fumes are present. Keepers and any other living creature must also be well away from fumigation sites.
Incubators will run better if kept in a room with a stable ambient temperature. Incubator rooms should be well away from any tampering and staff should always announce their presence before entering as a quickly opened door can startle technicians and cause problems should eggs be being handled at the time.
If the incubator room has windows care should be taken to ensure that sunlight does not fall on the incubators at any time. A blind at the window will protect incubators from overheating due to direct sunlight.
Egg Handling
Egg collection has been dealt with earlier. However it is vital that all keepers should thoroughly cleanse their hands before either collecting eggs or handling them during incubation. Disposable surgical gloves or sterile rubber gloves should be used wherever possible.
If possible it is better to avoid washing or wetting eggs as external bacteria can quickly be absorbed through the shell into the egg. Very dirty eggs can be carefully scraped clean with a sterile scalpel blade. They can also, once surface dirt has been removed be wiped clean with a sterile dampened cloth. It is possible to obtain a commercially made egg disinfectant used in the poultry industry, this can also be used if absolutely necessary.
If hand turning eggs or candling eggs, they should only be turned slowly and gently. Quick, sharp movements when turning can damage eggs. Eggs should only be turned 180 degrees. Mark eggs on two opposite sides with arrows facing one another and only turn the egg the way the arrow showing points, until the other arrow is uppermost.
Once eggs have had a certain amount of incubation and are proved to be infertile by candling they should be removed from the incubator to prevent cross infection of viable eggs. Having an incubator solely for suspect eggs is useful.
Position, temperature and humidity
Some people incubate eggs on their ends, with the pointed end down. Some prefer to let the eggs lie naturally on the side. Most commercial incubators turn the eggs up to 24 times per day. If an odd number of hand turns is added - 3, 5, 7, not only does it mean that the incubators and eggs are checked regularly, but the eggs will get at least that number of full turns and should spend the longest break on a different side each day.
Raptor eggs have been hatched in incubators at varying temperatures, but the most used and seemingly most successful is 99. 5 f - 37. 5 c with between 30 and 35% relative humidity, however this may need to be changed if an egg is either loosing too much weight, or not enough. All known species of birds should lose 18% of the fresh egg weight by the time they hatch, 15% of this weight loss should have occurred by the time the egg has pipped.
Often the most difficult thing to measure is the fresh egg weight (FEW) Unless each egg is weighed as it is laid, it impossible to know the FEW of a clutch of eggs that is removed from parents after say 10 days of natural incubation. A formula from the Peregrine Fund has been made by Burnham By carefully measuring the egg ( Several times in differing areas as no egg is perfectly symmetrical) both the length and breadth with callipers, the following formula can give and estimated FEW.
W = Kw (LB2) where W = fresh weight
Kw = observed weight
coefficient for peregrine
eggs (0,0005474)
L = Length of egg (mm)
B = breadth of egg (mm)
A sample calculation for an egg 50mm long, 40mm in breadth would look as follows:
W = Kw (LB2)
= 0.0005474 (50 x 402)
= 0.0005474 (80,000)
= 43.79 grams
This calculated FEW can be in error by as much as 2%, however, this is not normally enough to affect the hatchability of healthy eggs. Although this formula has been worked out for Peregrines, it seems to work well for other species.
Eggs begin to lose weight as soon as they are laid. So by various calculations the estimated, desired weight loss can be approximated. By weighing all the eggs at regular intervals Keepers can see whether or not to change the humidity to increase or decrease weight loss. For further information see references.
It is advisable for keepers or technicians responsible for incubation to gain experience on Chicken eggs through every stage of egg handling and incubation before going on to more important species.
Incubation Periods
The majority of raptor eggs hatch in 28 to 35 days, the larger species can go as high as 55 to 60 days. It is strongly recommended that all eggs thought to be viable are given continued incubation at least one week over the known incubation period.
Some chicks will become very vocal close to pipping and whilst still in the egg. Sometimes movement can be seen as the embryos start to get active, others make no sound or movement until the pipping process has begun. By hand turning on a regular basis pipping eggs should be spotted soon after the shell has been cracked. With the more strongly coloured eggs such as the falcons the first crack may be difficult to spot, however it can usually be felt by running a gentle and clean finger round the egg.
Once an egg has pipped it should be moved to another incubator for hatching, particularly if other eggs are present, but not hatching. Turning ceases and the egg should be placed so that the pip is uppermost. The hatching incubator is run at the same temperature (99.5.f - 37.5.c) but the relative humidity is raised to 55 to 60%. After the egg has pipped there will be an interval of rest for the chick, some will enlarge the pip area to a hole and can be seen moving, others may have no movement until actually starting to turn. This period can be very worrying for the technician, but patience is needed, particularly by those new to the experience. Interference too early is often not needed and can be fatal to the hatching chick. Once the embryo starts to turn in the egg the hatching process should only take from ten minutes to an hour. King Vultures are not inclined to move in the shell and often have to be helped after making a large hole.
If the hole has become too enlarged before turning commences the membrane may start to dry out and cause the embryo to become stuck and unable to move, spraying with a fine mist of warm sterile water, or painting with a soft, wet, sterile paintbrush can help the membrane to become loose. The hole can be covered with damp tissue or even a tiny piece of Micropore tape (remove some of the stickiness by placing on the back of the hand several times).
Once the chick has hatched the navel should be swabbed with an iodine based disinfectant. Never spray the embryo with a propelled spray, always administer it with a cotton bud or clean tissue.
The hatched chick can be left in the hatcher until dry or moved to a brooder straight away. A newly hatched chick has an oddly shaped head, a bulbous neck and very protruding eyes, all this will settle down within 24 - 48 hours. Some chicks may look very distended due to insufficient water loss, but this will dissipate if the chick survives.
Problem Hatching
Some eggs will prove more difficult than others. However only experience of the technician will be able to judge really well when to assist hatching embryos and when to leave well alone. Assisted chicks are usually weaker in the first few days of rearing, may need extra care and even a course of antibiotics.
The general rule of thumb for the inexperienced is leave the egg pipping for sixty hours before attempting to help the embryo to hatch. However as experience is gained assistance can be given earlier if required. If the egg experiencing problems is candled and the air sac marked on the shell with a felt tip pen, small parts of the shell can be removed with forceps. Be careful not to pull off any shell touching the membrane.
Once the membrane is exposed, if it is touched with a wet, sterile paint bush full of sterile, warm water the blood vessels will be exposed. Then the technician can see if the blood supply is still flowing or has closed down. By gently touching the most obvious vein with the tip of the paint brush and then removing, this will become very obvious. Completely closed down vessels contain no blood, Once that happens it is usually safe to carefully remove the embryo.
If the blood is still flowing, cover the hole with the exposed membrane with damp tissue and place in a still air incubator, not a forced air as this will dry out the embryo too quickly. Keep checking until the blood flow has ceased. If helping out a chick, don’t remove straight away from the lower part of the shell. Ease the chick to one side and see if the yolk sac has been retracted, if not - leave the embryo in the lower half of the shell until it has - this could take another twelve hours. To keep the embryo from sticking, or getting infection the lower half of the shell can be gently damped with a mild disinfectant The chick will be prone to getting cold at this stage so deal with it either in a very warm room or on a water proof heated pad, and keep the temperature of the still air incubator at 99.5 f. until the chick is safely out and dry and warm.
All problem chicks will need extra care and probably extra fluid.
2.4.4 Development and Care of Young
Brooding
Newly hatched chicks should be placed in a still air incubator or brooder running at 95.0 f. This temperature can be reduced by 1 degree a day until the secondary down comes through and young birds are able to thermo-regulate, or are returned to parents or foster parents.
It should be stated here that the Falconiformes TAG strongly recommends that all young birds should be reared by parent or foster parent birds. Total hand rearing should be avoided at all costs. Unless bred specifically for demonstration work, or artificial insemination, hand reared individuals are unlikely to be potential breeders, can be very aggressive and take up valuable space. This does vary between species and some of the vultures will breed if hand reared as long as they are subjected to visual or physical stimulation of their own kind as soon as possible.
Newly hatched birds should be put in containers that are designed to hold legs neatly tucked under the birds. Splayed legs can happen in a matter of one hour if birds are kept on the wrong surface. A plastic 1/2 gallon ice-cream or margarine container, with at least two inches of sand formed into a hollow with a fist and covered in two pieces of kitchen towel is ideal. This should be placed in the brooder at least 24 hours before needed will provide a warm and stable nest cup for young birds. The kitchen towel can be replaced after each feed and the cup can be reformed.
If rearing a number of clutches of young raptors, it is probably easier to have several brooders at constant known temperatures and move the growing young rather than altering the temperature of one brooder. Overheating can kill very quickly, a good, tested thermometer should be reading the temperature close to the young at all times. A steady temperature in the brooder room makes the rearing of young much easier. It is not advisable to have young in the same room as incubating eggs as young birds are considerably less clean than eggs and cross infection could occur.
Various brooding methods have been tried, still air incubators - although these are excellent they are only suitable for the first few days of life with all but the tiny species, or problem young. A disposable card-board box with heat lamp, washable plastic containers such as water tanks with the bottoms cut off and either overhead heat lamps or low heat plastic veterinary recovery pads underneath containers. Heated water pads ("K-Pad" - available in USA) that young can move up to or away from, all have their merits and breeders should find out which is most suited to their needs and budgets.
As long as care is taken to keep young clean, warm, well fed and on surfaces that will allow the correct growth, that is all that is needed.
Young that are too cold will huddle together and cry. Young that are too hot will pant, spread out away from one another and also cry, but it is different noise. Experience will soon tell the technician what is needed. Over heating is more likely to lead to weak and ill young.
With all but the smallest of species supplemental heating should not be required after 10 days if the brooder room is at 70.F (21.C) and no lower.
Containers should be washed daily to remove build up of faeces.
Feeding
More young raptors are killed by overfeeding than any other cause.. Unless dealing with tiny young, such as Pygmy Falcons or other young weighing less than 10 grams at hatch, it is best to leave the first feed for at least twelve hours and sometimes longer if the chick is showing no signs of hunger. Newly hatched chicks that look distended with fluid should be left without food until the stomach is flaccid and soft to the touch.
A mixed diet of finely minced or chopped meat is suitable for most species. Quail, skinned, gutted with the gizzard, feet, wings and head removed, rabbit skinned, gutted, feet and head removed, rats treated the same way, plus chop off the tail, day old chicks, skinned, yolk sac, gizzard, head and feet removed, mice skinned: when put through a commercial mincer these make excellent food for young raptors. The bones will be utilised by all but the youngest of chicks and these can be pushed to one side when feeding for the first couple of days. A probiotic supplement giving the beneficial bacteria and microbes should be added to the feeds for several days for young chicks. ‘Avipro Paediatric’ made by Vetark is specially designed for this purpose and contains a starter kit for newly hatched birds at their first feed.
Using forceps tiny pieces of minced food can be offered to the chick which should raise its head to accept feeding. Falcons need food to be placed in the beak, often with the upper palate being touched by the food before they will close their beaks and swallow. The rest of the raptors, with the exception of the New World vultures will respond to the food being brought in slowly towards the beak at about their eye level and will then attempt to snatch the food from the forceps. Young chicks are pretty inept to start with, missing the food, or falling over, however they soon get strong enough to take food more easily. The New World vultures naturally feed by putting their beaks inside the parents beak and receiving regurgitated food. By gently encircling the beak with finger and thumb the adults beak can be represented and then the young bird will take food from forceps touching the side of the beak.
Vultures seem to do better if a digestive enzyme is added to the food as well as a paediatric probiotic. Damping the food for all young raptors makes feeding a little easier and keeps young birds from getting dehydrated. Apart from the smallest of young (the under 10gms hatch weight) four feeds per day is sufficient to give good weight gain and growth rate. To keep a check on the health and growth of young birds they can be weighed regularly. Weighing before and after every feed gives a good idea of food intake and growth.
Rings
Once young birds have reached 10 to 14 days old, most of them can be ringed. Although there is no legal requirement for most species, it is advisable to ring all but the New World vultures, as this gives an external way of marking and keeping track of captive birds. Closed rings can be obtained from good commercial producers and they know most of the correct sizes required. It is a legal requirement to ring some species and the rings for these are obtained from the Department of the Environment, Transport and the Regions. See Legislation 2.7.
Casting Materials
Casting materials to allow the young bird to form pellets for regurgitation can be introduced to the food at about 10 days to 2 weeks, for small to medium sized birds and up to one month for larger ones. Just stop skinning the day old chicks and that will give sufficient. Casting material is not vital in the early stages, in fact the birds could probably do without it until feathering up. The adult birds very carefully select the pieces of food they think the young can manage and usually fur or feather is thrown aside or eaten by the parent. It is vital to feed the bones and minerals that come with mincing whole, yet gutted and skinned, animals. Small birds such as merlins do better without casting material until they are feathering up.
Supplements
Added vitamins and calcium can be very useful. Many collections may have to use frozen food items and some of the goodness is lost in this process. A good multi vitamin supplement should be added in powder form on the food - do not exceed recommend doses. Calcium has to be used carefully, sterilised bone flour can cause imbalances in phosphates. The most highly recommended is Nutrabal which seems to work well in raptors without causing any problems if used as directed.
Water
Young raptors do not drink until they have left the nest and can reach water for themselves, however they not only obtain water from the meat they eat, but the parents drip an oral secretion onto the food while feeding the young. As stated earlier, by damping or dunking the food prior to feeding the chicks, with either water or a ringer’s solution will stop dehydration and assist growth of young.
Age of returning young
Once young birds have reached 10 to 12 days, are looking healthy, eating well and have been ringed, they should wherever possible be returned to parents or foster parents.
If this is not possible then all through the rearing the young should have as little in the way of contact and handling from the humans caring for them. Puppets shaped to the colour and build of the adult can be used to assist in avoiding any severe imprinting on keepers. Most species will learn to pick up food for themselves at about 10 days old. Encourage any young that are having to be totally hand reared to learn to feed themselves as quickly as possible and spend as little time as possible exposing them to human interference.
If the young are going to be put back not so much care is required to avoid human contact as it will soon be forgotten once the birds are being reared by their parents. If returning the young is left much longer than 14 days they will be mobile enough to try to get out of the nest in fear when they first come face to face with their parents.
First time parents are an unknown quantity and keepers should always make sure that they have plenty of time set aside on the day chosen to return young. Birds will have to be watched for several hours, possibly for one or two days to check that all is well. Some birds are really difficult to monitor as they will not do anything while under observation, these birds can may to be watched from a distance with binoculars.
Two keepers, both wearing a falconry gloves should be available to return the young. The young ready to be returned should be placed in a bowl for ease of carrying to the aviary. Returning the young is much the same as taking eggs. One person fends off the female with the net while the other removes the eggs and replaces them with the young. If the parent birds have been sitting on dummy eggs, these need not be handled carefully, however if the birds have recycled and are sitting on fertile second clutches, great care must be taken in removing the eggs. A moment still by the nest ledge to watch the first reaction of the parent birds is advisable. If you are really lucky, the female will immediately come up to the nest - watch for her ‘balling’ her feet - and may even cover the young straight away. The enclosure should still be observed as the reaction of the male has to be assessed before keepers can relax. If the female takes to the young it is rare for the male to cause problems, however it can happen and should a young bird be picked up or grabbed by either of the adults action must be taken. Keepers should run towards the enclosure and bang loudly on the side while someone goes in to rescue the youngster..
What more often happens is that the two adults will sit away from the nest watching the new young and probably wondering what has happened to their eggs. The keeper can only watch and wait to see if either parent will go down to the young. It can be a good idea to leave fresh food on the side of the nest to encourage feeding.
Eventually most birds will show some sign of reaction. It is very rare for birds to completely ignore the young and refuse to sit, or feed the young. If that does happen a decision has to be taken whether or not to leave the young in the nest over night. That will probably depend on the weather conditions, if it is very warm and the keeper can be around at first light to monitor the enclosure then the young can be left. One day without food will not harm them at this stage and sometimes the calling done if they get a little cold or hungry will bring a favourable response from the parents. More than two days probably means that a different approach will be needed the following season and young will have to be removed and placed elsewhere.
A bad reaction from a parent does not necessarily mean that they will never be a good parent - it just takes more time and management to get things right for that individual pair. Once a pair has made it as successful parents it makes things much easier so that the effort put into achieving results is well worth it.
Don’t forget that if the eggs removed are the second clutch they should be swiftly and carefully taken to the incubators and placed there safely while others watch and safeguard the returning of the young.
Foster Parents
Most Buteos will rear any other species of buzzard, hawk, eagle. or other similar species. Most falcons will rear any falcon, although species size should be taken into consideration. It is unwise to ask very large species to rear the young of very small, even though related species. If keepers stick to using falcons for falcons and mixing buteos, accipiters, and the eagles, for rearing any of those families it has been proved to work. Don’t forget that some young from eagles will indulge in cainism if not treated in the correct manner.
Some species really need their own kind as parents or fosters. Common Caracaras have a fairly bare face and once full, a very bare crop, this is a little too different for only distantly related fosters. It also means that what might be termed ‘odd’ species may not be able to be mixed with the young of the more ordinary species for the same reasons.
Monitoring
Once young are successfully accepted by parents or fosters they should be monitored to check there are no problems. On rare occasions chicks in stick nests have got a twig caught under the ID ring - this does not normally cause problems if seen early but can damage a bird permanently if left unnoticed. In clutches of two or more, one young may just not be doing as well, removing either chick and hand feeding it for a few days should solve the problem, the chick can then be returned to the nest.
Great care should be taken entering aviaries or nest areas once the chicks are close to flying. Young birds bailing out of the nest too soon can injure themselves.