Table 1. Distribution of Lear’s Macaws in the managed population

Participating institution	Country	Status*
Al Wabra Wildlife Preservation	Qatar	4.5.0
Crax – Wildlife Research Society	Brazil	1.1.0
Harewood Hall	United Kingdom	1.2.0
Loro Parque Fundación	Spain	2.2.0
Lymington Foundation	Brazil	2.4.0
Rio de Janeiro Zoo	Brazil	6.5.0
Sao Paulo Zoo	Brazil	3.5.0
	Total:	19.24.0

In the studbook (Reinschmidt 2006) are seven participating institutions with 43 officially incorporated birds (Table 1). These are the birds which currently form the managed captive population which is under the coordination of IBAMA, the birds being on deposit from the Brazilian Government. There is an additional living specimen confiscated by the competent authorities in Brazil in October 2006, which will be incorporated  into the managed population.

There are a further two female living specimens also likely to join the official population. There are an undisclosed number of Lear’s Macaws in Switzerland, for which there is no definite prospect of their inclusion in the officially managed population.

Demographically the managed population requires a breeding momentum to add more young birds, as can be seen from the age pyramid (Figure 1), and improvement of the current sex ratio of 0.74, by the addition of more males. However, the breeding programme is necessarily at an early stage. Because most of the macaws have been recruited to the population as confiscated young birds taken in their first year of life, there are close estimates of the ages, even though they are registered in the studbook as wild-caught. Furthermore, endoscopic examination of the condition and stage of development of the gonads of these birds reveal that at 7 to 8 years of age they are only just entering reproductive maturity (L. Crosta and L. Timossi, in litt.). This coincides well with the first studbook registered breeding occurring in 2006 at Al Wabra Wildlife Preservation in Qatar, which holds the oldest birds.

Figure 1. Age pyramid of the managed population of Lear’s Macaws.

Given that 42 of the studbook registered macaws are wild-caught, founders apparently constitute 97.6% of the captive population, a remarkable and positive situation. However, given that these macaws have been taken from nests, and often were confiscated together, there is a reasonable probability that the founders (which by definition should be unrelated) include siblings. However,despite this possibility, the genetic situation overall in the Lear’s Macaw studbook is favourable, as can be demonstrated by work in progress of Prof. Cristina Miyaki and her team at the Institute of Molecular Genetics, University of Sao Paulo. Dr Miyaki has carried out DNA analysis from blood samples obtained from these macaws, and has been able to calculate a genetic similarity index between all of the individuals. Thus she has all possible pairings ranked according to the statistical probability of genetic relatedness of the birds (in five ranks, from lowest relatedness = A, to highest = E).

In general terms (scientific details, Miyaki et al.,in prep.) this indicates the following. The macaws sampled (17.21) have a total of 357 pairing combinations, which show 115 (32.2%) in the low relatedness categories (A,B), 131 (36.7%) in the medium category (C) , and 111 (31.1%) in the high categories (D,E). Currently, all 17 males with known similarity indices are paired with females, with relative proportions of genetic relatedness as shown in table 2. The same table indicates the changes in these proportions if re-pairing of macaws takes place within each institution, i.e. before interchange of macaws between institutions. The pairings according to institution are shown in table 3.

Table 2. Pairings of Lear’s Macaws in the managed population: level of genetic relatedness currently and after re-pairing within each institution.

Table 3. Level of relatedness in possible re-pairings of Lear’s Macaws within each institution.

Given that in the first instance it is easier to manage species populations on a regional basis, it would make sense to exchange birds for further re-pairings between the holding institutions in Brazil. From the 11.15 captive Lear’s Macaws currently in Brazil, it is possible to make 11 low-relatedness (A) pairings. Any intention to re-pair these birds must take into account the compatibility of the individuals within pairs, revealed primarily by their behaviour, and following precautions:

2.Aim for most genetically acceptable pairings, but before breaking existing pairs take breeding history and age into consideration.

Acknowledgements

We thank Prof. Cristina Miyaki for making available the rankings of relatedness of possible pairings.

References