Modern Captive Breeding–Part IV

Jan 15, 2012 by  Admin

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0nce eggs successfully start to hatch then the propagator’s work really begins. Yet again a little preplanning will greatly assist in this, the most labour intensive area of captive breeding. Chicks hatching under parents will require close monitoring and for those hatching in incubators where a modicum of hand rearing is needed, a regular schedule of feeding and cleaning is needed. The rearing methods and nutrition employed for each chick over the next couple of months, will have a heavy bearing on its physical and physiological qualities for the rest of its life.

HAND REARING

Neonatal raptor chicks are semiartirical and thus require an outside source to provide warmth and nutrition (usually its parents). To successfully handrear chicks from hatching the three main areas that need to be addressed are:

 

1. Temperature Control

2. Nutrition

3. Hygiene

Temperature Control

Due to the 100% humidity level within the egg, a freshly hatched chick will be wet at the time of hatching, and should be left to dry in the hatcher for several hours. The chick will appear weak and pathetic at this point, but with several hours rest it should soon start to perk up. Raptor chicks are unable to self control their own body temperature post hatching, so provisions have to be made via the use of a brooder to keep the chicks warm.

On visiting many breeding projects, I am regularly disillusioned

simply a thermostatically controlled pad, containing warm water. A towel is placed over the pad and the chicks are placed on the towel. Some breeders are sceptical of this system, as most of the heat is generated from below the chick. However enough breeders use this system exclusively to make it worth considering.

Once dried, the chicks are moved from the hatcher to the brooder which is holding a temperature of 36.5°C (98°F). At the same time each chick is colour coded using a felt tip pen on their backs and, or top of the head for individual recognition purposes. Each chick is placed into its own thoroughly cleaned open topped plastic container (130 x 80 x 60mm), with several pieces of kitchen roll as a substrate.

We never mix buteos or accipiters with falcons in the same brooder. This is due to aggression from the shortwings in the form of the `Cain and Abel’ battle. Eyass shortwings will fight from the second day of life, to establish a hierarchy within the nest and once a chick is overcome by its aggressor, it will lie still with its head down and the battle will cease. Falcons do not fight, so if attacked by a shortwing a young falcon will keep lifting its head until it is severely injured or killed. If you do keep them in the same brooder make totally sure they cannot reach one another.

The brooder temperature should be decreased gradually. The rate of decrease will depend on the species being brooded. As an example gyrs and Peales peregrine come off heat at a lot faster rate than barbary or lanner falcons. There is no magic temperature that any eyass should be kept, but their behaviour will indicate whether they are too warm or too cold. Chicks which are too hot

will lay stretched out with their legs out behind them or on their all their brooding systems. These same projects have installed state of the art incubation systems with all manors of fail safe systems, only to put their hatchlings into what can only be described as `Heath Robinson brooders’. These range from homemade still air boxes through to a single light bulb. When one considers that a two day old chick will die from hypothermia faster than an egg would perish due to loss of its heat source, it should be obvious that the quality of the brooding is at least as important as the incubator the chick was hatched in. There are times when all propagators should stand back and look at any areas which may be a potential `weak link’ in their breeding strategy, and this seems to be a common one.

There are numerous good quality brooders available on the market today. Over the last four years we have used the `Animal Intensive Care Unit’ (AICU) manufactured by Lyons Electrical Company. This unit has proved to be very reliable and fulfills all the requirements we need.

Another suitable brooding method, is the Kpad system. It is side with legs out stretched to their side (this can be an initial cause of splayed legs). The most obvious sign is the chick panting. The major sign of a chick being too cool is when it is sat hunch backed and vocalising with a groaning sound. This behaviour is generally observed just after feeding, but should cease within fifteen minutes. A common cause of chicks failing to turn their crop over in the expected time can be due to the brooding temperature being too cool.
Nutrition Nutritionally, a freshly hatched chick is fuelled by the yolk sac, which has been drawn into the abdomen just prior to hatching. No attempt should be made to feed the chick until it will voluntarily beg for food. To initiate a feeding response from a young falcon simply `chup’ at it and it should then lift its head and gape, waiting for food to be placed in its beak. The feeding technique for accipiters and buteos is totally different as they respond visually to the sight of food held within tweezers directly in front of them and will lurch forward and snatch at it. At first, their sight to snatch coordination can be a little haphazard but they soon get the hang of it. The period of time from hatching to the first feed will vary enormously between individuals, from as little as two hours up to fifteen.

Individuals, which have had problems hatching, may be weak and dehydrated and will require fluid replacement both orally or via subcutaneous injection.

When considering nutrition, the tyro breeder is faced with a number of questions, What type of food to feed? Plus what amount and how often does the eyass require feeding?

As to the type of food, the easiest line to take is to ask oneself what type of nutrition a chick needs, at each stage of development. As an example the nutritional requirement for a twodayold peregrine is totally different to the needs of a tenday

old eyass. During the first three clays of life the major growth and development takes place in the digestive system and the liver, so small easily digestible pieces of meat are required. Hence we feed small pieces of lean quail meat from the chest or leg muscle.

From the third clay, the diet is changed to finely minced fullbodied carcasses. This falls in line with the start of major skeleton growth where calcium and other nutrients are required. Our diet from this point consists of 50% prime quail mixed with 50% laboratory rat. All food is prepared once daily, split into four and refrigerated until used. Each carcass is skinned, the head, feet, wings (where applicable) and digestive tract removed before being finely minced. At the time of feeding, a small amount of warm water is added to warm up the food and to lubricate the food for easy swallowing. The eyasses are kept on this diet until they are either put back with parents, or if being imprinted, are pulling large items of food for themselves. Some breeders state that roughage should be included from around day ten, we have not found any problem with excluding this until they are feeding from complete carcasses.

When unfamiliar with hand rearing eyasses, it is human instinct to over feed. A very common cause of death is from over feeding, this may be due to either too greater quantity of food being fed at a single meal or by feeding too often. From the time of hatching we feed the majority of our eyasses four times daily with approximately five hours between each feed. With small raptors such as merlins and sparrowhawks we increase this to five feeds at fourhour intervals. No eyasses are fed through the night. The quantity of food fed at the first feed should only be three pinhead sizes of meat. Then four at the next feed and so on. Once enough food is being fed as to discernably see it in the crop, then the crop must be checked at the beginning of each feeding session to make sure it is empty before the chick is fed

again. If food is still in the crop, do not feed for a further hour depict how much the chick is eating and its weight gain since the last meal. Several breeders have published a number of weight gain charts, plotting a specific chick’s growth. Although these are very interesting, it is important that direct comparisons between them and your own chick are not made. Too many outside parameters such as type of food, amounts fed, frequency of feeding, brooder temperatures, humidity levels etc. will affect a chick’s growth trend for any true comparison to be made.

We try to get as many eyasses back with parents by day seven as possible. Not only does this cut the workload down but we

have also found that the parents can do a better job at feeding than we can from this point in development. Experience has shown that if we feed a chick at this stage while food from the previous meal is still in the crop it usually leads to major problems. But an eyass only has to yawn under a parent and it is fed, crop full or not with no adverse effect. How parental birds get away with this feeding behaviour is a mystery.

Hygiene

As with incubation, hygiene is of paramount importance when rearing eyasses. Raptors have little natural immunity to outside pathogens, particularly those they may meet in the alien environment of a brooder room. Brooders should be kept as clean as possible with any substrate changed regularly. Close alliances should be made with an avian vet prior to the breeding season, as if a chick shows signs of illness, immediate medical assistance must be at hand. Any chick showing signs of illness must be quarantined away from the others immediately.

Food storage bowls, feeding utensils and the propagator’s hands must be clean and sterile (as possible) before any contact with the chick. Common problems like splayed legs can all be eradicated by using the right sized brooding tub and substrate. Unfortunately, some breeders have taken the direction of the prophylactic use of antibiotics when rearing some species in particularly merlins. This course of action is usually based on problems, which have occurred in previous seasons. My own

opinion is that if we can only breed certain species with the Placing back with parents

Placing chicks back with parents, particularly for the first time, can be nerve racking. But again there are certain safe guards you can take to at least improve you chances of the chicks being accepted. Over the years we have experienced all manor of behaviour with parents when chicks have been introduced, from perfect acceptance through to all out aggression. It is important not to place eyasses back with parents at too later stage of development. Small and medium size raptor chicks will show fear responses toward parent birds if introduced beyond 14 days of age. Generally we place all our eyass falcons with imprinted females to start with (around day 7), some will stay with these and others will be moved on to natural pairs at around the twelveday stage. By placing the chick with an experienced parent for a few days teaches it to feed and act normally around a parental bird, this is a great help when finally placed with a novice parent.

A natural assumption is to try parents with a single chick to start with, however slightly aggressive parents are more likely to attack a single chick than a group of them. With this in mind

we always place at least two chicks in with first time rearers. One option is to try parents with young kestrels if they. are available.

When introducing chicks back with parent(s) for the first time, we try to choose a warm morning and with the eyasses slightly hungry, so as they will soon solicit feeding. Watching the parental bird’s behaviour should give you an idea of their intentions. When dealing with imprints the whole scenario is a lot easier as you are in the pen and it is easy to intervene should there be problems. A common occurrence is for the female to gently bite at the chick’s neck and sometimes they pick the chick up with their beak and walk across the nest ledge, very much to the chick’s annoyance. However if there is any sign of the parent grabbing with a foot, intervention is needed immediately as this is outward aggression. On a number of occasions when we have tried individual imprints with chicks for the first time, they have totally ignored them, even when left with them for several hours. Some of these falcons have been tried several weeks later and took to rearing duties immediately. One female barbary refused to rear for her first three egg laying years, on trying her in her forth season she took to rearing like an old pro.

When positioning falcons in our imprint pens, we try to place one yearold females opposite older experienced birds. Through their respective widows they can look across the service passageway onto each other’s nest ledge. We soon noticed that several of the voting female peregrines would vocalise and try to pass food through their bars as they observed the older falcons feeding chicks. Once this behaviour is seen we introduce a couple of chicks in with the young falcon, which has resulted in a number of oneyearold peregrines rearing chicks.

This occurred again last year and due to having a lot of chicks of the same age, the young peregrine ended up with a brood of five their first year, but if they do, they should be given the chance. Although not suitable for brooding young chicks, some male imprints will rear chicks, if introduced once they are past the brooding stage.

When dealing with natural pairs of some species, in particular goshawks and merlins, it is not uncommon for the male to be aggressive with chicks. Subsequently Some breeders remove the male from the breeding chamber prior to introducing chicks.

We try wherever possible to rear pure species under a female of the same type. This will help in the chick’s perception of his or her own species if destined for future breeding. From learned behaviour it is often seen that eyasses reared under a female who is of a nervous temperament, will themselves he more reserved when first manned for falconry and viceversa. When rearing chicks in open fronted chambers this learned behaviour can lead to problems. If we take a pair of Harris’ hawks rearing chicks, any aggression or fear shown toward dogs etc. that they view, will lead to the eyasses having a deep distrust in them (even more than they usually do).

All eyasses should be left with their parents until at least two weeks post hard penning unless they are destined for a wild hack.

Independence Chamber

A small number of eyasses when manned, immediately after being removed from the parents may start to show classic imprinting signs. I put this down to the eyass switching its dependency from its raptor parents to its new handler. With this in mind, once two weeks post hard penned we started to move eyasses into a independence chamber away from both their parents and any human contact. These pens are constructed as large as possible to assist in early flight lessons and to accomplish a modicum of fitness. But the major advantage of these chambers is the eyass has to learn to look after itself and gain a more independent state of mind. We regularly keep up to 25 eyass falcons in each chamber for the short period.