Latest update on the Hyacinthine Macaw Project

by Tony PITTMAN. Published in the Parrot Society Magazine, 1997, Vol. XXXI

I have just received the latest annual report for the Hyacinthine Macaw project managed and operated by Neiva Guedes setting out the results and findings of her work for the period 1st January 1996 to 30th April, 1997. This lengthy document is summarised as follows for Parrot Society members.

160 nest sites were monitored out of a total of 193 available sites on the 21 ranches of the survey area in the southwest Pantanal. Of these 96 were used by Hyacinthine Macaws. 95 eggs were laid in 55 of these nests. Nineteen nests with eggs were lost, mostly through predation. Altogether 55 young were produced by 36 pairs, of which 37 fledged. Most of the young were examined, weighed, measured, given rings and had blood taken for DNA analysis.

In addition studies were carried out in differing areas of land management on the density of manduvi trees (Sterculia sp.), the main nesting tree of the Hyacinthine Macaw in the Pantanal. Proposed studies with radio collars had to be postponed because the collars ordered from Canada did not arrive in time. 8 individuals received training during the period and work continued on informing and educating local people through presentations and radio broadcasts.

One great achievement was the successful rearing earlier this year of a young macaw in the artificial nestbox built by the group of German aviculturists in June 1995, set up by Neiva in July/August 1995 and used for the first time by a pair of Hyacinthine Macaws in the breeding season 1995/6. We discovered two eggs in this box during the nest inspection tour in January 1996. Sadly the young hatched from the two eggs laid in this first season were predated. We were therefore delighted when the box was used again by the same pair, this time with such success.

Nest sites

The 193 available nest sites mentioned above were located in four separate districts - 124 on 12 ranches in Nhecolandia, 35 on 4 ranches in Abobrai, 32 on 4 ranches in Miranda and 2 on 1 ranch in Nabileque. Of the 152 nest sites monitored in 1995, 15 (10%) were lost. 10 were lost because either the tree or the branch in which they were located fell down. The remaining 5 were artificial nests, which were destroyed by the macaws or bad weather. However 25 new nest sites were discovered, 60% of which were in the Miranda district with most on the Caiman estate.

As stated above 160 nest sites were monitored, 143 natural and 17 artificial. Most natural nest sites were found in the manduvi tree, which as reported in earlier articles has a soft core and forms cavities readily. Other trees with nest sites included angico-branco (Albizia niopioides), angelim (Vatairea macrocarpo) and a scientifically unnamed species known locally as maria-barriguda.


The monitoring of the nest sites by Neiva revealed the level and nature of the competition. 61 were occupied by Hyacinthine Macaws, 12 by Green-winged Macaws (Ara chloroptera), 3 by Black Vultures (Coragyps atratus), 12 by bees (Apis melifera), 3 by the Collared Forest Falcon (Micrastur semitorquatus), 1 by the Muscovy Duck (Cairina moschata) and 1 by the Toco Toucan (Ramphastos toco). Of the remaining 67 nest sites, 29 were not used for no discernible reason and 38 disputed.

35 of these nest sites were disputed by the Hyacinthine Macaws with other species, 13 with Green-winged Macaws, 6 with Black Vultures, although the latter usually breed earlier so that the nest site is vacated for the macaws, 5 with the Collared Forest Falcon, 4 with bees, 2 were disputed both with Black Vultures and bees. 3 nest sites violently disputed with Toco Toucans and for the second year running broken toucan skulls and beaks were found in a nest cavity. Even when the macaws succeed in occupying the nest site, the toucans may predate the eggs or chicks before taking over.

2 sites were disputed with Muscovy ducks, who normally use the nest sites after the macaws have finished breeding. Problems occur when the breeding period of the macaws is delayed. This year for the first time a dispute was observed, which lasted for four months. A dead female duck was found decomposed in the nest site and removed, but the dispute continued with another duck.

Nest site management

Neiva has found the number of monitored nest sites occupied by Hyacinthine Macaws averaged out at 50% in the period 1991 to 1996. The competition is becoming more intense particularly in those areas where deforestation is on the increase. Repair work to damaged trees is therefore an important part of the project's activities. 13 such damaged trees were repaired during the period under review. 2 artificial nest boxes of recycled natural stumps were set up. This is demanding, time-consuming work ,which is also quite dangerous because of the size and weight of the boxes as well as the height at which they must be affixed. Hyacinthine Macaws bred successfully in four of these repaired, managed natural sites. No success was achieved by the macaws in the 2 artificial boxes set up in 1996, although a pair of Blue-fronted Amazons (Amazona aestiva) actually bred in one.

Reproductive biology

As mentioned above 36 pairs produced 55 young, of which 37 were successfully reared by 30 pairs.. 19 pairs produced two young, but only 7 pairs succeeded in rearing them both in 1996. There is at present no discernible pattern to the survival of two young in one nest. In 1995 a pair had two young, one much older than the other. The older sibling was growing fast and gaining weight, whilst the other was losing weight and failing. The younger macaw was taken out and hand fed for two days. When returned it was still not fed by the parents, so the older one was temporarily removed and the following day the younger chick had a full crop. It was then transferred to another nest with a young macaw of a similar size and age where it thrived and fledged.

In yet another nest in 1996 there were two young with a ten day age difference. The difference in size and weight was considerable, but both survived and fledged. In another nest with a similar situation, the smaller younger macaw did not survive. Neiva also came across a case of dwarfism in a nest with two young where the younger was half the size and weight of its older sibling although the age difference was very slight. However, both survived and fledged.

6 young were predated and the suspected predators were either Toco toucans, Collared Forest Falcons, caracaras (Polyborus plancus), Great-horned Owls (Bubo virginianus), coati (Nasua nasua) or irara (Eira barbara). Two more nests suffered chick mortality through sickness for unknown reasons. The mortality rate in 1995 and 1996 was higher than in previous years with 18 dying in 1996. Thus the reproductive success for breeding pairs has dropped from 1.29 young per pair in 1991 to 1.03 in 1996.

Green-winged Macaws, which are also monitored by Neiva, occupied 26 nest sites in 1996 and laid eggs in 14 of them. 16 young were hatched, of which 14 fledged.

The future

Nest monitoring will continue this year as will repair work to damaged trees. At the end of May another small group of German aviculturists visited the Pantanal with Thomas Arndt for hands-on conservation experience. More artificial nestboxes were constructed and mounted. Next year (1998) I shall accompany a mixed group of German and British aviculturists to work briefly on the project.

Nearly 200 nest sites have been located on 21 ranches over a wide area, which demands much from a very small team no matter how dedicated. Radio collars will be fitted to four of this year's young and a camera installed in a nest to identify predators, particularly of eggs. In addition to all this the educating and informing process will be continued.

Finally this report concludes with an unusual occurrence. On August 26th ,1996 Neiva decided to cut a new entrance hole in a tree where the nest cavity had become far too deep. The previous year she had not been able to examine the young in the nest. When the team arrived, a pair of Hyacinthine Macaws defended the nest site for some minutes before flying off. Neiva thought it was a pair exploring nest sites for the new breeding season.

The Brazilian zoo technician assisting Neiva at that time carefully made a new opening lower down the tree in case there were bees within and was amazed to discover a Hyacinthine Macaw inside the tree. When the macaw was brought down they discovered it was fully grown, but with broken feathers on the tail and wings. The plumage colour was normal, but the bare skin areas and the stripe on the tongue were very pale. It weighed 1,271 grams and measured only 445 mm from the head to the end of the tail instead of the usual one metre. The wing-length was 310 mm and the tarsus 42.8 mm, the latter being normal for an adult. The crop was 50% full. The macaw was rung and returned to the nest. The following day the nest was monitored again and it was decided to remove the macaw on the next day.

It was taken to Campo Grande to the Animal Care Centre to be looked after and give it time to grow back its tail and wing feathers. When these are fully developed it will be returned to the tree it was originally bred in.

It is now clear that it was trapped in the nest hole for many months, but had been fed by the parents birds throughout. At first when given acuri nuts, the main diet of the Hyacinthine Macaw, it did not recognise them or know how to crack them. It could, however, eat from nuts that had been broken open and within a few days was handling whole nuts like an experienced adult.

Ref: Relatorio Technico Anual do Projeto Arara Azul, 1996 by Neiva Maria Robaldo Guedes dated 20.4.97

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( If you drive out nature with a pitchfork, she will soon find a way back)

Horace (65-8 BC)