Modern Captive Breeding–Part I

Jan 14, 2012 by  Admin

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In this and three further articles I will be giving information on the captive breeding of birds of prey. I will be referring to all the major knowledge and practical skills areas. My aim will be to provide a basic grounding. However even though I have given me more space than is often possible in a web-site, it is important to note that only the major points can be conveyed and that in many cases there is substantially more detailed information to be imparted.

This additional information will be available from a variety of sources and if you stay with me until the fourth and final article I will give you some pointers in that direction. In this first Article I will cover commitment, planning, choice of breeding stock, housing and nutrition.

In addition to being of help to the tyro propagator, I also hope these articles will give some indications to falconers on how much time, effort, planning and cost is involved in producing a quality eyass raptor. From the falconers’ point of view, it is well worth bearing in mind that the quality of the young bird produced by a breeder for the falconer, will depend on the quality of the rearing processes and nutrition used. This will translate into the bird’s performance in the field later on.

Commitment and Planning

When starting to plan any breeding programme, bear in mind that success is directly proportional to the amount of work, time and effort you are willing to put into the project. It is assumed for the purpose of this series of articles that the raptors you are aspiring to produce are for falconry use, and/or for future captive breeding. Before beginning you should consider carefully before taking on the task of captive breeding. As well as the cost both in financial terms and in time, if you are the type who gets uptight or upset when things go wrong, then this is not the pastime for you. After personally experiencing all the ups and downs (and there are more downs than ups) of captive breeding, it is easy to see why most falconers take the option of not bothering to breed their own birds. During the mid eighties, with raptor prices spiralling, quite a few people jumped onto the captive breeding bandwagon. It seemed an easy way to make money. Many found this was a cloud without a silver lining, and having paid big prices, produced nothing. If financial reward is your major incentive, rather than a byproduct of your breeding success, 1 strongly advise you to invest your money in something else. Also keep in mind that good falconers do not necessarily equate to successful raptor propagators. Although a good grounding in falconry is required, it is avicultural skills, albeit specialised ones, that have to be learnt.

The first choice to be made is what species you intend to breed and by what method of propagation. I will not be presumptuous and recommend a species, as this is purely down to an individual choice. Although no raptors are easy to breed, if from the human angle, you are a beginner then you will find that the Harris hawk and Saker falcon are two of the easiest species to persuade to reproduce.

When choosing a species, the long-term requirement of that species within the falconry community also has to be taken into account. For instance, in the UK the common Buzzard has been a primary choice of the novice falconer for a good few years and rightly so. However, with the increased number of captivebred Harris and Redtail hawks available today at very modest prices, the Buzzard is now being overlooked. So why breed a species that nobody wants? Sure, some people will want Buzzards in the future, but my own 24 year old pair have averaged 4 young per year for the past 20 years and that’s a lot of prospective new owners to find, believe me.

It is also worth considering concentrating on those species you are especially interested in, as my view is that if the interest is lacking then results in terms of productivity will reflect this.

Like any commercial breeder of raptors, 1 have to endeavour to predict what species and in some cases subspecies, falconers are going to want to buy in the future. I must also consider the needs of all of my customers, whether it is a friend from Arabia who wants a Gyr hybrid for Houbara hawking, an experienced falconer in the UK who wants a Gyr hybrid or Peregrine for game, or a beginner who wants a Buzzard or a Harris hawk to make a start.

Initial Breeding Stock

The acquisition of the initial breeding stock is one of the most important decisions to make. My own preference is to obtain young birds and wait for them to mature. Indeed 90% of our stock, which equates to around 100 birds were either bred by ourselves, or obtained in their first few months of life. 1 can see why the tyro propagator obtains adult individuals or proven breeding pairs to try and speed up the chance of success. In the majority of cases where we have taken this route, results have been poor. If an adult bird is to be obtained, it is imperative that a full history of the bird is known (how was it reared? was it used for falconry? has it been tried for captive breeding?). By obtaining your breeding birds as youngsters you are in control of their subadult history and as will he seen through this series of articles, the more control you have, the better the chance of success.

So, the next decision is whether you intend to breed from natural pairs or by the use of voluntary artificial insemination with imprinted raptors. The use of imprints is increasing in popularity with breeders here in the UK but it is fair to state that the main success with imprints has been with falcons, and to a lesser degree eagles, rather than accipiters and buteos.

Choice of Birds for “Natural Pair Breeding Projects”

So lets look at methods of rearing young raptors for future ‘natural breeding’. In the UK there has been a long history of “fully parent reared is the only way to go!” This is generally understood to equate to young raptors reared from hatch or at least ten days of age, by parent birds in a breeding pen, void of human contact. However my experience is that birds reared in these circumstances are comparatively nervous and “jumpy” in the breeding pen when they reach adulthood. If you do choose fully parent reared birds for a “natural pair” breeding project then you will find that birds reared in seclusion, stand a far better chance of breeding if flown for falconry first. The reason for this is all down to stress levels. It’s quite simple, birds that feel stressed in captivity don’t breed. This is because hormones produced when a bird feels stressed such as adrenaline suppress the production of sex hormones which are required for the bird to come into breeding condition.

The fully parent reared approach is great for birds destined for a career in falconry such as hybrids, and some birds will of course breed via this rearing method, but when it comes to maximising your chances, the two most productive methods of rearing for future captive breeding are:

1. Rearing by imprinted birds with a certain amount of human contact.

2. Hand reared in large groups often known as  creche reared or cohort raised.

Both of these methods will be covered in the ‘rearing’ section in a future article.

Choice of Birds for imprinting

If the use of imprinted birds is your chosen method, then I strongly recommend that whenever possible you imprint the bird yourself. I keep around 50 imprinted falcons and with a couple of exceptions the ones I imprinted myself are more productive than the others. Other breeders have also found this to be the case. When importing imprinted birds from a breeder, it is worth asking if the breeder has the necessary time available, to imprint the bird properly, as commercial breeders in particular are very busy at that time of the year. An alternative is to pay a falconer from the country of export to do it for you. The money will be well spent to receive a bird that is imprinted correctly.

Picking the Individuals.

Once you have chosen the species you intend to breed the next decision is to pick the individual birds. There are two points to take into account. The first of these is a falconry one. For the breeder it is imperative that as much information on the parent birds is obtained on previous progeny produced by them with regards to their falconry successes. Information on size, weight and colour are all questions rightly and commonly asked when people ring us for a falcon. Sometimes people also ask how good its siblings and parents performed in the field, and what style of flight they produced, and in my view this should he a major consideration. This is something we are working to develop at Falcon Mews and as time goes on we will be able to give more and more information in the area of falconry performance. By speaking with the breeder and other falconers who have had experience with that lineage, a close assumption of its falconry style and potential can be made. All too frequently a small difference in the price of individuals swings the buyer towards one bird, but if the individual bird doesn’t fit your requirements, it will certainly result in a false economy in the long term.

The second point to consider is the performance of the lineage in the breeding chamber. Again some detective work will have to be carried out. For example some Goshawk lineages have proven far more productive, with less aggression problems than others, even after being reared and kept under the same parameters.

I find that a lot of our regular customers who are ordering falcons for falconry purposes, order falcons bred from specific parents which have previously produced top hunting performers, rather than just a particular species. With this in mind, the days of pairing any individuals up just because they show signs that they may breed have long gone. I now have to plan specific breedings, to accomplish eyasses of a specific standard. Selective breeding is the only way forward.

The breeding chamber

When planning and building pens, it is essential that you cheek if any planning permission is required. A great deal of practical thinking should be put into planning of your pens and you should aim to think through all of the following: siting, dimensions, access arrangements, building materials, flooring materials, nest ledge design, perches, food ledges, observation methods, baths, and security needs. Pressure of space means 1 can only touch on these areas, but some key considerations are as follows:

Siting will depend on your circumstances but obviously major considerations are accessibility for you, and if you can choose somewhere relatively unexposed to the elements so much the better. With regard to size a lot of breeders state very specific dimensions and designs for breeding pens, and the tyro may assume that if these are deviated from, then the occupants will refuse to breed. This is totally untrue. The main requirement is that the raptors feel safe and at ease within their chamber. Dimensions should he down to what you believe is sufficient, strongly taking into account the occupants ‘quality of life’. 1 believe that medium sized raptors, paired for natural breeding, should have a chamber with a floor area of at least 20 x 10 feet and at least 8 foot high and higher if possible. Our imprint pens are all about 12 x 8 feet in size.

We are quickly moving away from the ‘skylight & seclusion’ type chamber and providing our pens with a window to look out of. The amount of close visual disturbance that is present in your particular circumstance should dictate whether or not you fit a window. The window can be a vertical bar affair or simply a oneinch diameter hole for the birds to view out. A window is still probably not feasible under most circumstances for passage caught accipiters in breeding projects, owing to their nervous nature.

When it comes to choice of materials, this to a certain extent comes down to cost, though of course you must always aim to use the best you can afford, and never use materials which are poor quality or unsuitable for the job. For example fence panels should never be used as they fall short on both quality and strength. We tend to build using concrete blocks and/or exterior plywood. We now only build pens with solid roofs as we find this type of pen more appealing to both the inhabitants and ourselves. This is particularly true when dealing with imprints, as you want to spend time with these birds when you want, and not be dictated to by weather.

Probably the most difficult problem to overcome is the type of floor to use. Earth floors in outside pens can over time harbour disease. Concrete floors soon get green and slimy. Pea gravel seems to be the best answer but is still not ideal. We use dust free pine wood shavings in our inside chambers. Numerous people who have visited us have questioned the use of shavings on the basis that it may be a possible source of aspergillosis. We have had no instances of this, even with species kept on them that are very susceptible to the complaint i.e. Goshawks, Golden eagle and Gyr falcon. If the shavings are kept dry then fungal problems should not occur. Indeed fresh pine is a natural disinfectant.

Nutrition

Very little scientific research has been carried out into raptor nutrition. Of all the areas of research needed in raptor propagation this is at the top of the list. The difference between an average diet and one approaching optimal nutritional requirements can be the difference between being successful with your propagation attempts and failure. Suboptimal diets can manifest themselves via infertility, poor hatchability and weak chicks through to no breeding activity at all and in severe case disease and illness in the adults. Numerous falconers have viewed a general concern that captivebred birds seem to be getting smaller. This is not something I have noticed in my own birds but enough falconers have commented on this with regard to birds bought elsewhere for it to be an issue. One answer generally given is genetic inbreeding, but although this could he a reason 1 believe suboptimal nutrition at the time of rearing, to be a more realistic answer.

To the novice, a diet that is as close to the bird’s wild prey would seem to be the ideal choice. Well, apart from the problems of obtaining the prey source in sufficient quantities and the health risks associated with wild food, is it nutritionally adequate for the captive raptor? We believe it isn’t, for the following reason.

There are around forty known nutrient requirements (and probably more) which a raptor receives from its prey. These consist of fats, proteins, minerals, vitamins and trace elements. In the wild, the energy requirement of a raptor dictates the amount of food, which it needs to eat. So if for sake of argument and as an easy to follow example, a wild female Peregrine eats 300 pigeons per year to meet its immediate energy requirements, which is obtained from the protein and fat content from the pigeons. At the same time it consumes all the vitamins, minerals and trace elements from the pigeons it requires to keep the body functionally correctly. Once the Peregrine enters a breeding pen its energy requirements drop. To fall in line with this drop, and based on my experience, the Peregrine now eats up to a third less food, so it now eats 200 pigeons. The problem is that all the vitamins, minerals and trace elements have also been reduced by a third. It is not known precisely what levels of these the raptor, requires for the body to function correctly, but it’s almost certain that this shortfall of a third is far too much.
So the ideal diet is one with an energy level, which meets the raptors immediate needs and contains all the other nutrients at the sufficient levels required. This is where the two areas of research are required. First, what are the exact requirements of these levels, and second what food source can be produced in captivity and under what dietary conditions do they need to be fed, to reach the levels required. Of course this is impossible to work out exactly, as the requirements will vary for different From the point of view of the falconer buying a young bird for hunting, nutrition is obviously crucial as it affects the quality of the bird and its subsequent performance in the field. An eyass Harris with a calcium deficiency which breaks its leg on its first hunting day out, means a ruined hunting season as well as being heartbreaking from a personal point of view. In extreme cases problems can occur even before the bird gets to the field. Some propagators go for the cheapest option where nutrition is concerned, and the results can be seen when observing their progeny, if they have managed to produce any. A simple test asto whether an eyass has

received enough calcium in its diet, is to run your finger the whole length of the breastbone. If any bends or chinks can be felt, particularly towards the bottom of the sternum, then this is a positive sign that the calcium level received during its growing period was insufficient.Some Concluding Thoughts

With the proliferation of raptors, bred and offered for sale each year, it would appear to the ill informed that all aspects of raptor propagation are straightforward and any initial problems have now been totally overcome. This is far from the truth. After breeding various raptors for twenty years and reflecting on all the information and experienced gained, there are still questions to be answered. More research is needed, particularly into areas such as nutrition, and hopefully Falcon Mews and other breeders will have the opportunity to carry out this research in the future.

In the next article in this series I will be covering breeding behaviour, and voluntary and involuntary artificial insemination.