Modern Captive Breeding–Part II

Jan 14, 2012 by  Admin

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For anyone considering beginning a breeding project, a decision has to be taken on what approach to take. Generally speaking, this will depend on the amount of time and resource you are able to put into the project. 1f’ you have limited time then a natural breeding project might well be your choice. The main advantages are that far less time is needed in terms of observation and interaction with the birds. The disadvantage is that fewer birds are likely to be produced and you will have far less opportunity to produce specific types of bird, and in the case of’ specific hybrids use of’ Al is the norm. Of course for many aspiring raptor breeders this will not be an issue, as they will be aiming simple to produce enough birds to meet their own falconry needs, and perhaps, also those of a friend or two. On the other hand it’ you are aiming for a commercial operation, or to selectively breed e.g. different hybrids from the same female, then you will almost certainly want to acquire the skills needed to collect semen from male raptors and inseminate the female.

NATURAL BREEDING

By far the most popular method of’ captive breeding in the UK is placing a pair of birds in a suitable breeding chamber and hoping that nature takes its course. To the tyro breeder the initial act of releasing two birds into a chamber is generally quite daunting, as fear of aggression and fighting is generally in the forefront of their mind. The truth is that this rarely occurs if the birds have been reared correctly in the first place. In the case of falcons, buzzards and eagles a few threat displays and some mild harassment may occur, but this should sub-side over a short period of time. In the case of accipiters however, they should be kept in adjoining pens with a window between them and only allowed together once both birds show full breeding display. It always amazes me why this double pen system is accepted for goshawk breeding, but is used less often for sparrowhawks, especially when you hear how many muskets are killed by their intended female partner.

Best time to pair up.

We are often asked to advise on the best time to pair birds up. Our approach at Falcon Mews is, if possible, to put birds together in the early autumn. This allows time for them to settle into their accommodation and become used to the daily sights and sounds of their new environment. Stress, or rather lack of it, is crucial to successful raptor propagation whatever approach is used. So the more time to settle in the better is the general rule. Of course there are many falconers who want to fly their birds and then breed from them in the non – hunting season. The question then is how long can the hunting season go on before pairing up. We have currently bred from Harris hawks and peregrines paired up in late January, but rule of thumb is that the earlier you can put the pair together the better the chances.

Birds put together late in the season who do not breed can be tried earlier. Once a successful pattern has been established it can usually be followed with success every year. Bearing in mind the importance of the stress factor, it is probably true to say the species which are naturally tamer such as Harris hawks can be paired up later, though there are always wide variations amongst individual birds. Another factor to take into account is that there is variation in the breeding season between different species. For example lugger falcons often lay in February whilst merlins lay in late April or early May.

We always place pairs into a breeding chamber or pen at the same time. It is not a good idea to place a male into a chamber where the female has been resident for any length of time as she may show territorial aggression toward him. All birds should be approaching or at top weight when paired up.Compatibility and natural attraction.

The question of compatibility between paired raptors has often been debated. One school of thought is that, if both birds reach a high enough breeding condition, then they will procreate. However, if they are not at ease with their mate, the stress level and hormonal imbalance which associates itself with stress, will suppress the hormones which are required to bring the bird into breeding condition. There is also the question of natural attraction. Forecasting this is extremely difficult if not impossible and placing two birds into a breeding chamber is a bit like a blind date, sometimes they work and sometimes they don’t. Natural attraction in raptors definitely exists, and this is recognised by some of the world’s leading breeders of gyrs and peregrines, who have pioneered a very successful method of pair selection for large falcons. This involves placing several unrelated pairs of eyass falcons in one large pen together. A single nest ledge is put in the pen and the birds are observed closely over the first eighteen months of life. As soon as a pair takes over the ledge territory, and defends it against the other inhabitants, the other birds are removed from the pen. Thus, the pair have had the choice and chosen their mate.

Observation of breeding behaviour in natural pairs.

Close observation is required to assess what breeding behaviour is taking place. This should begin in January or February at the latest. You should undertake some research before beginning observation to check what behaviour should be occurring if all is well. There are now numerous articles and papers written on a multitude of breeding successes with different species. Unfortunately, if you read accounts written on a particular species bred in captivity it is easy to fall into the trap of expecting your birds to be doing exactly the same. It should be remembered that all birds are individuals and although a species will follow similar breeding patterns there are variations. For example one pair of peregrines we breed from are very vocal when copulating, whereas another pair we have, don’t make a sound. Some male Harris hawks are ardent nest builders and others never pick a stick up, but yet both can be equally productive in the eyass production stakes.

Period of time from start of courtship to egg laying.

The period of time from when the first sign of courtship begins through to egg laying will vary enormously, not only between species but between individuals within a species. First time breeders usually start their courtship slightly later than experienced pairs but in subsequent seasons they will start earlier and for a longer period.

Age at which different species breed.

It is generally considered that parental stock bred in captivity, regularly breed at younger ages than their original wild taken ancestors. A few examples of this are golden eagles breeding at three years of age, prairie falcons at one and Gyrs as young as two. The general view on this is that if the right conditions are created, stress levels can be lower in captive-bred birds and nutritional intake higher. This phenomenon has occurred in the captive breeding of many other species of birds such as psittaciformes.

ARTIFICIAL INSEMINATION

Semen Collection.

The two methods of obtaining semen are by manually stripping a male or by an imprinted male copulating on a human voluntarily.

With regard to the technique needed to strip a male raptor, there are written descriptions, but you should certainly aim to see it done by an experienced breeder. The quantity of semen given will vary not only from different birds, but also between each stripping session from the same bird. Although the stress involved in being caught up and manually handled is kept to a minimum, most males will only stay in breeding condition if stripped every couple of days or so.

For an imprinted male who voluntarily copulates with its human mate there is no stress involved. Our voluntary males donate semen at least twice daily for up to two months. To give you an example of what one of these males is capable of, during the past breeding season, a three-year-old white jerkin that voluntarily produced semen for the first time this year, managed to fertilise forty-five eggs for us. This is by no means a record, but when you realise that up to forty percent of his semen was

not used, it gives you a good idea of what a good voluntary donating male is capable of.

We do not have space here to go into any depth on the techniques used to produce a male voluntary donor, but in very basic terms it involves interaction with the imprint male on a daily basis to establish a strong bond between human and bird. The human “partner” mimics breeding behaviour of a female of the same species of the male. Typically this involves the human partner copying as far as possible the breeding display behaviour of the female by making bobbing movements of the upper body and or hand, and by making noises which simulate the breeding call of the female. This has to continue until the bird reaches sexual maturity and maintained for as long as semen is needed from that particular bird.

When the breeding season arrives, the males are encouraged to copulate and deposit semen onto a hat, glove or pad of a suitable size and shape to suit the male. This is designed and made of a suitable material to ensure collection of all or most of the seuieu deposited. You will find that the quality of semen produced by different males varies enormously. Some males produce excellent for many years, but variations are possible even in the best producers. Most breeders, to assess quality, use microscopic examination of semen. It is important to note here the importance of having some back up in any breeding project, which relies on semen collection by stripping or voluntary donation. If you have several females, but only one male who produces semen, then you are risking all on one shot. The answer is either to have a team of males or to make arrangements with a fellow breeder to provide “mutual insurance”. This is a real issue and even projects with a number of males can find themselves short of semen at particular times of the season. This tends to happen in particular at the start of the season. There is nothing that will drive you up the wall faster than having two or three females begin laying but no semen to inseminate.

Voluntary A.I. with imprinted female raptors.

The use of voluntary Al with imprinted female raptors has grown enormously in recent years. Although its use has mainly been with falcons and to a lesser degree golden eagles, some success with accipiters is now being achieved, particularly with goshawks. Apart from being the most stress free (for human and bird) approach, voluntary AI can be a highly productive method of propagation. To achieve this desirable state of affairs, the breeder must be prepared to put in a substantial amount of time with the female imprinted raptor from an early stage in the bird’s development. This is necessary to give the best possible chance of establishing the strong pair bond between human and bird required to make voluntary

insemination possible. Generally speaking the earlier the process of imprinting begins the better. We like to start with our female imprinted falcons from ten days of age and daily interaction with the `human partner’ continues from that point. To be successful, the human must have fully or very largely assumed the role of the male bird. The technique used to produce an imprinted female who will stand for voluntary insemination is similar in many ways to that used to produce a male semen donor. Again pressures of space do not allow me to go into any greater depth on the techniques used. In general terms the whole process can be divided into three stages – the first stage is the initial hand rearing and imprinting. – The second stage is from fledging through to the birds first breeding season. Many breeders find that flying the bird for falconry is a very productive procedure, as the bird is handled daily and the close bond between falconer and bird that is established is the perfect catalyst for this type of breeding. The other approach is to keep the female imprint in a pen and visit her several times daily to reinforce the bond and ensure that no fear response toward its human mate is allowed to occur.

The third stage is the breeding season itself. In the majority of cases the female will lead you through the whole process and start soliciting copulation as you enter the breeding chamber. It is not unusual for the female to start soliciting for the first time, after laying one or two eggs during her first egg-laying season.

It should be noted that if either of the first two stages are not

fulfilled, then the last stage will not occur. When you have

reached the point where the female will allow you to place your hand on her back while she presents herself for copulation then you can feel confident that the imprinting process has been

effective enough to make voluntary AI a success.

When things go well it is possible to produce many fertile eggs from the same female. It is not unusual to be able to produce ten or more eggs from one female falcon and to achieve 100 percent

fertility.

Voluntary AI is generally only achieved with `human imprinted’ individuals. However raptor breeders know of many exceptions to this rule.

For example, a few raptors, which have come into falconry from the wild, as adults, have been known to exhibit exactly the same behaviour towards the falconer as captive bred imprints. This leads us to ask m questions as to how much we really know about the psychological side of imprinting. There are several theories but that will have to wait for a later article.

Involuntary AI

Involuntary AI is an approach normally used when the other two methods are not going right for reason. It might be that you have a pair intended for natural breeding but over several years, although eggs have been produced none have been fertile. In this case involuntary insemination of the female can transform a totally unsuccessful I project into a very successful one. The other situation where involuntary AI is used is where a female imprint intended for voluntary insemination, refuses to stand correctly. In this case the use of involuntary AI can produce success rates almost as high as that achieved by the voluntary imprint. Skill in carrying out involuntary insemination is something, which takes some time to acquire and master, and even then some people will always be better than others. It is essential that you see it done by an experienced practitioner before attempting it. It is also true to say that the more inseminations you do the better you are likely to become. Views on precisely the right technique vary even amongst the most experienced breeders, but most manage to achieve a high level of fertilisation. Timing is a crucial factor as it is preferable to inseminate the female within two hours of her laying, so constant observation is required.