Boland Falconry Club

HYBRID RAPTORS – A CONSIDERATION OF THE ISSUES.

(THIS DISCUSSION DOCUMENT DOES NOT REPRESENT POLICY OF ANY ORGANISATION)

Background

Falconers started to breed hybrids almost as early as they could breed falcons. The first well-documented case of captive breeding being the saker-peregrine crosses produced by Ronald Stevens in 1971.

The first crossings were mainly to show that falconers really could breed falcons: Hybrids could not readily have been taken from wild pairs.  In the USA, hybrids produced by Jim Weaver gave impetus to the creation of the Peregrine Fund and its release program.

Particular crosses may have advantages for falconry, in providing quality flights in circumstances and surroundings where pure-bred birds are more likely to fail.

In artificial landscapes of modern countries, hybrids may allow falconry to continue in places and at quarry which were previously impractical.  In desert countries, hybrids of gyrfalcons are preferred to pure-bred sakers or peregrines because they are larger and faster, and less stressed by heat than gyrfalcons.

Concern about hybrids centres on loss into the wild of domestic hybrids or species that may hybridise in the wild.  Falconers have always lost some birds, and are skilled in the deliberate releases that have frequently been used for conservation.

Although radio-tagging has now made accidental loss a rare occurrence, the hacking of untrained domesticprogeny, as a means of improving flying skills, may create a greater risk of losing hybrids than after they are trained.

The extent of concern depends on the type of hybrid, which may be between species that occur together in the wild (sympatry), between species that occur in adjacent areas (parapatry) or between species from geographically isolated areas (allopatry).  Concern may also depend on the health of local wild raptorpopulations, and is likely to affect public perception of falconry.

Sympatry and parapatry

Species that occur in the same area or adjacent areas, such as gyrfalcons, peregrines and sakers, have opportunities to breed together naturally.

Behavioural and physiological mechanisms usually prevent them hybridising, although occasional natural raptor hybrids have been recorded.  In the long-term, traces of such rare hybrids are likely to be eliminated by natural selection, possibly aided by physiological mechanisms.  Therefore, no risk can arise from pure-bred species hybridising with sympatric or parapatric species after loss by falconers.  This statement is valid for any sub-species a species may have, because a species is defined as a population of individuals with natural gene flow between them.

However, hybrids of sympatric or parapatric species that have been bred by enforced proximity or artificial insemination may lack natural isolating mechanisms.  They may cause problems if either their genetic fitness is higher than that of native birds or if lost in numbers where natural populations are depressed, for example in areas where peregrine populations have not recovered after the pesticide era.  In such cases, natural selection through competition is reduced, and hybrids may tend to persist in the wild.  They may also have added strength during the interference with breeding that occurs naturally in healthy populations.  There are many reports from Germany of such interference by hybrids, and hybrid falcons have produced young in Germany, Sweden and the United States.  Some records probably result from hybrids that disappear while at hack with inadequate precautions against loss.

Allopatry

Some sympatric or parapatric species allopatric species, which are from geographically isolated areas, lack natural mechanisms that prevent hybridisation.  An example is the American Ruddy Duck, which hydridises with the European White-Headed Duck and aggressively displaces it following release at wildlife parks. Agreement has now been reached to try to eliminate the Ruddy Duck in Europe.  It is too late to eliminate the Mallard from North America, where its hybridisation with the native Black Duck has produced such a large “hybrid swarm” that pure Black Ducks may be lost entirely. Thus, pure-bred species introduced to an area they could not reach naturally, or hybrids between allopatric species, sometimes prosper at the expense of a less robust native equivalent.

In raptors, which are very mobile creatures, allopatry is likely only between the American and Eurasian super-continents, Australasia and oceanic islands.  Among raptors of wide interest to falconers, the only species with less robust allopatric equivalents are Red-tailed Hawks (for Common Buzzards in Europe), and Sakers (for Prairie Falcons in North America).  Falconers have avoided producing hybrids between allopatric raptors.  Red-tails are not hacked and Sakers only in their native Eurasia.  Harris Hawks, flown widely in Europe, create no risk because there is no closely related ecological equivalent.  Compared with deliberate release of wildfowl, it has long been accepted that there is negligible risk from rare losses of single trained raptors.

Public relations

Although natural selection should eventually eliminate hybrids, it may not act fast, and if many hybrids are lost they could represent a small proportion of the total wild population at any time.  This might offend people who worry about wild raptor populations.  Falconry is at present fairly well understood across a spectrum of conservation organisations, for whom sustainable use is becoming an important part of conservation.  This improved understanding recently gave falconry explicit exemption from Bern Convention constraints on use of exotic species.  Moreover, falconers are gaining increased access to wild populations in some countries, which reduce motivation to fly non-native species.  At a time of growing cooperation in conservation, it behoves falconers and other groups to engage positively to handle any issues arising from production of hybrids.

Position Statements

In a recent Position Statement, the Raptor Research Foundation (RRF) reviewed the main biological issues affecting falconry, which is the largest international organisation specifically for research and conservation of raptors.  RRF’s position was that “escape of sympatric or parapatric species or their hybrids is unlikely to pose any significant threat to wild populations”, but that “hybrids between allopatric species (defined as from different super-continents) should not be bred for falconry” and that steps should be taken to reduce risk of breeding by any lost hybrids.  It also noted that, to avoid wasting conservation resources, the intensity of regulations on falconry should be consonant with the risk to raptor populations.

A recent review by the Advisory Committee of the International Association for Falconry and Conservation of Birds of Prey (IAF) endorsed this position.  It was concluded that current regulations and practices are adequate to prevent risk to raptor populations from hybrids. However, IAF was concerned to preserve its positive relationships with other wildlife interest groups, and therefore also issued a Position Statement on the subject.

The Position, on Hybrid Raptors in Falconry, of the  International Association for Falconry and Conservation of Birds of Prey

The International Association for Falconry and Conservation of Birds of Prey (IAF) has examined in depth the practical and theoretical considerations that arise from the production of hybrid raptors.  After a review of the available data and taking expert advice, we consider it unlikely that a problem for wildlife conservation will arise from the breeding of hybrid raptors if their loss to the wild is rare.  We recommend, as a minimum, that:

1. hybrids be fostered if possible by a parent that does not occur locally in the wild;
2. hybrids only be hacked in large conditioning pens;
3. hybrids only be flown with telemetry equipment;
4. maximum efforts be made to recover any hybrid that is lost;
5. hybrids should never be deliberately released.

We ask IAF member clubs to bring these considerations to the attention of falconers’ worldwide. We accept that individual clubs may feel obliged to endorse stricter measures.  However, we strongly believe that self-regulation is preferable to regulatory supervision.  In that spirit, we appreciate a growing tendency of falconers in some countries to fly purebred falcons rather than hybrids.  We are keeping this issue under review and will remain actively involved in the political consultation processes at all levels of regulation.

Adopted by the delegates of the member states at Amarillo, Texas, on 21 November 2000.

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