LINKED PAPER
Captive breeding cannot sustain migratory Asian houbara Chlamydotis macqueenii without hunting controls. Dolman, P.M., Collar, N.J. & Burnside, R.J. 2018. Biological Conservation. DOI: 10.1016/j.biocon.2018.10.001. VIEW
I started working with the Sustainable Houbara Management project in 2013 as a field assistant in Uzbekistan where I cut my teeth in the methods of studying this elusive species, Chlamydotis macqueenii, from finding nests, catching birds and fitting satellite transmitters. Since then I have been fortunate to manage the field research programme and I have followed the birth, life and sadly sometimes deaths of more than 100 individual Houbara. In that time I have grown in awe at how tough, elegant and for better a word, magical, the Houbara is. I can only just begin to understand why it is ingrained so deeply into the Arab culture for, like the Bedouin of the Arabian Peninsula, it is a desert specialist moving with the seasons to survive in the harsh desert environments. It is a symbol of a cultural past that is fast becoming lost and this is perhaps why there is a race and huge investment in the captive-breeding and release of Houbara as an effort to prevent its possible extinction.
Houbara breeding facilities have popped up around Asia. Some of these have a huge amount of expertise and budgets, meaning they can produce up to 34,000 birds a year. To put this in context, the global population of Asian Houbara was estimated as 79,000‒99,000 in 2014. As a consequence of this, the tradition of Arab falconry has continued with no flyway scale regulation. There is also illegal killing by local residents of the range countries (which of course is unregulated) and also live trapping that occurs through Iran, Pakistan and Afghanistan for the falconry industry. To date there has been no evidence-based assessment of whether or not captive-breeding and release is an effective strategy to allow the persistence of Asian Houbara under the status quo of current rates (whatever these are) of exploitation.
This is the essence of the work that the University of East Anglia (UEA), BirdLife International and Emirates Bird Breeding Center for Conservation (EBBCC) partnership has been carrying out since 2012. The aim is to create an evidence base for sustainable hunting, addressing in particular the contributions of captive breeding and in situ management. EBBCC is a small-scale breeding centre in Uzbekistan that has a hunting concession in the Bukhara region. The hunters from the Emirates that hold the licence to this concession contacted Nigel Collar, of BirdLife International and Chair of the IUCN Bustard Specialist Group, to work with them to find a sustainable solution to houbara hunting, in order that falconry and the Houbara upon which it depends can continue into the future. He, in turn, contacted his long-time collaborator Professor Paul Dolman at the University of East Anglia to lead on the research.
Image 1 Captive-bred Houbara chick. © RJ Burnside
Seven years of intensive work studying every aspect of the demography of wild and captive-bred birds in Uzbekistan, using a combination of field-craft, nest monitoring and satellite telemetry (to quantify survival) has now allowed the first scientific assessment that addresses the role of captive breeding in making houbara hunting sustainable. The results are published in the journal Biological Conservation this month (November 2018).
Using demographic modelling, we found that the Asian Houbara is still declining, at an average rate of 9.4% per year. The work showed that this decline was mainly attributable to high winter mortality of both adult and juvenile Houbara. In fact, more than 50% of the winter deaths were attributed to hunting or illegal killing (Burnside et al., in press). The breeding productivity in Uzbekistan was actually very good during the period of study, with no obvious opportunity for in situ management to increase it further. Therefore, the alternative in situ option to address the decline, would be to reduce the high winter mortality. Modelling sequential reductions in hunting mortality showed that the current rates of hunting are 2.5 times a naturally sustainable rate (Fig. 1).
Figure 1 Mean population growth rate (lambda) with 85% confidence intervals under different rates of reduction in hunting and poaching. Values above 1 mean the population is growing and those below mean it is declining
Next, we explored ex situ strategies, quantifying, how many birds would need to be released within the Bukhara province to stabilise the population. By following the fate of captive-bred birds fitted with satellite transmitters we discovered that the majority are lost in the first year to post-release mortality or during their first migration (see my first BOU Blog). Consequently, for near-certainty of success, it would require releasing 6200 birds per year into the study population (Fig. 2, N.B. figures just show females, and we assume a 1:1 sex ratio). That is 1.3 times the size of the wild breeding population! If there was a quota to hunt 200 birds within the Bukhara concession every year, 7600 birds would have to be released (Fig. 2). That’s 1.5 times the breeding population and effectively would more than double the density of birds upon release. It is staggering to think of.
Figure 2 Mean population growth rates (lambda with 85% CIs) with increasing numbers of captive bred (CB) houbara released into the Bukhara population, under two scenarios: of no hunting in the concession, or a quota of 100 females (200 birds) per year. Values of lambda above 1 show the population is growing and those below mean it is declining. N.B. points are offset horizontally for clarity. Large vertical arrows show the point where there’s an 85% chance the population will stabilise
Apart from the mammoth task of breeding this many birds every year to prevent the decline of a single breeding population, there are risks which have not yet been ruled out and these should be scientifically assessed. Several recent studies have shown that captive-bred houbaras do differ from wild counterparts in important demographic traits; as noted, long-term survival is suspected to be lower than in wild birds (linked paper); migration strategies differ from wild birds (Video 1; Burnside et al. 2017; see the BOU Blog); and some important reproductive parameters are lower than in wild birds (Azar et al., 2017, Bacon et al., 2018).
Video 1 Comparing Captive Bred with Wild Hooubara Migrations
There is currently no understanding of the heritability of these traits in houbara which may reduce the fitness of released birds. However, there is increasing evidence that captive breeding, whilst being successfully managed to prevent inbreeding and genetic drift, nevertheless selects for traits/genes that suit captivity, against traits desirable in the wild. So, the precautionary position must be to minimise the risk of undesirable traits introgressing into wild populations through the sheer weight of ongoing large scale releases. Otherwise, the end result could leave populations with no genuine wild breeding stock and reduce their capacity to be self-sustaining.
Additionally, there may be more immediate ecological risks, such as the density of birds increasing by more than double during the breeding period (when releases generally occur). This could have unforeseen consequences in terms of predator density, food availability and mate competition.
Image 2 Displaying male Asian Houbara © Andy Swash
So why not just hunt the captive-bred birds? Well, hunts tend to happen and releases occur within the migration corridor, and the breeding and wintering sites for wild birds. So by the time post-release dispersal and mortality have happened, the captive-bred birds are thoroughly mixed in with the wild population. Inevitably, therefore, wild birds still make up a significant proportion of the hunt bag (see the BOU Blog).
Lastly, we examined the question, what if international efforts were devoted to successfully regulating hunting and tackling illegal killing on the Central Asian flyway? Our modelling shows that a 60‒80% reduction in the winter mortality along with small-scale releases of captive-bred birds could stabilise the population while posing fewer risks from over-exploitation and introgression. Reducing the mortality rate through unilateral agreements between range states, moratoriums on hunting and addressing houbara trapping for falcon training will all go towards stopping the decline. Work has begun in this vein, after the Global Flyways Summit in Abu Dhabi (UAE in April 2018), when this work by the UEA team was first presented. Since then, the International Fund for Houbara Conservation (IFHC, GO from UAE) has recognised the need for focusing on tackling illegal killing with another global summit recently completed on 4 November 2018 involving 17 range states. This is an important step and really good news for houbara conservation.
Find out more about the Asian Houbara and sustainable hunting at the project website www.sustainablehoubaramanagement.org
Follow the project on Facebook, Twitter and Instagram @sustainhoubara
References
Azar, J.F., Chalah, T., Rautureau, P., Lawrence, M. & Hingrat, Y. 2018. Breeding success and juvenile survival in a reintroduced captive-bred population of Asian houbara bustards in the United Arab Emirates. Endangered Species Research 35: 59-70. VIEW
Bacon, L., Robert, A. & Hingrat, Y. 2018. Long lasting breeding performance differences between wild-born and released females in a reinforced North African Houbara bustard (Chlamydotis undulata undulata) population: a matter of release strategy. Biodiversity and Conservation. DOI: 10.1007/s10531-018-1651-6. VIEW
Burnside, R.J., Collar, N.J. & Dolman, P.M. 2018. Dataset on the numbers and proportion of mortality attributable to hunting, trapping and powerlines in wild and captive-bred migratory Asian houbara Chlamydotis macqueenii. Data in Brief. DOI: 10.1016/j.dib.2018.10.154. VIEW
Burnside, R.J., Collar, N.J. & Dolman, P.M. 2017. Comparative migration strategies of wild and captive-bred Asian Houbara Chlamydotis macqueenii. IBIS 159: 374-389. VIEW
Image credits
Featured image: Flying female Asian Houbara Chlamydotis macqueenii © RJ Burnside
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