Blue-and-gold Macaws in Tambopata, Peru.

Bird Talk, November 2000

03:55 Alarm goes off. . . It’s raining.

04:05 Alarm goes off. . . It’s raining harder, but it doesn’t matter. I still have to go out and observe the macaws.

04:10 I am up and fumbling around in the dark. Telescope. . check, binoculars . . check, data pad . . check, snacks. . check, chair . . where is the bloody chair?, nap . . no, no time for a nap. It is already 4:35 and I am running late. Rain gear, high rubber boots, flashlight and it is out in to the dark, wet, rain forest of southeastern Peru. My destination is the small palm swamp a 30 minute walk from my bed in the Tambopata Research Center. Here I am studying a small colony of Blue-and-gold Macaws (Ara ararauna) in order to better understand their biology and find ways to help increase their reproductive rates.

05:00 I have arrived at the base of the 45-foot observation tower in the swamp just as the rain is letting up.

05:10 I am settled in on my chair just as the light comes up, ready to watch the beauty of the 5 active nests of Blue-and-gold Macaws that surround me.

           The Blue-and-gold Macaw is a native of tropical lowland areas in eastern Panama, western Colombia, western Ecuador and most of the Amazon Basin in South America (Juniper and Parr 1998). Its great beauty has makes it a very popular pet and it is greatly sought-after by collectors through much of its range. This pressure combined with habitat loss, have resulted in the extinction of the species on Trinidad and its elimination from many areas of Ecuador, Columbia and Brazil (Collar 1997). The threats facing these and other species of macaws are grave and have resulted in the need to study the reproductive biology of macaws and develop techniques to help their populations recover from the decades of exploitation they have suffered. This article summarizes the work that has been done on Blue-and-gold Macaws at Tambopata Research Center, Peru. This work was spearheaded by Eduardo Nycander from 1990-1993 and by myself from August 1999 through today.

In 1989 when Eduardo and the research team founded Tambopata Research Center (TRC) Blue-and-golds were common visitors to the nearby clay-lick, but none were nesting in the immediate vicinity. It was known from other areas that the birds nested in dead palms, especially in the large palm swamps, or Aguajales, dominated by the Aguaje palm (Mauritia flexuosa). The ideal situation is where large stands of palms are killed leaving ghostly stands of dozens of dead palms. Under these conditions, many pairs may flock to the small area and nest in colonies. TRC has a small palm swamp, but when the research started, there were no suitable dead trees for nesting. In 1991 the team developed a technique to cut the tops off the palm trees in the hopes of attracting the macaws. Cutting off the top exposes the soft center of the palm to water, fungus, and beetles that all combine to rot the soft center of the palm away while leaving only the hard outer layers of the palm intact. This produces deep tubes perfect for nesting macaws. In mid 1991, 10 palms were cut and by November one had rotted sufficiently and was being used by a pair of Blue-and-golds (Nycander et al 1995). Since 1991, a total of 42 palms have been cut and they have been used extensively by both Blue-and-gold Macaws and Red-bellied macaws (Orthopsittaca [Ara] manilata).

           In November, 1999 I began intensive monitoring of the nests in the palm swamp at TRC. Screaming macaws heralded my arrival every day, showing me that the experiment was still working. I found that 11 palms were still standing. A close check revealed that all of the palms cut in 1991 and 1992 had fallen and that on average palms were lasting only about 4 years before rotting to the point where they fell to the ground. In addition, only 5 of the palms had rotted enough inside to the point of being deep enough for the birds to use. All five of these palms were used by Blue-and-golds and none were available for Red-bellied Macaws.

With a team of dedicated volunteers I worked to check the nests in the palm swamp once a week from November – March. We climbed to each nest using a variety of different climbing techniques. For some nests we used a variety of techniques to get up to these nests. For some we used two loops of climbing webbing, each attached to a ladder made out of webbing. To go up the palm the climber just had to slide the loop up the tree then climb up the ladder, then slide the second loop up the tree and continue climbing until reaching the nest entrance (See photo SWAMP 3). For other nests, especially those that were in palms too fragile to support our weight, we would attach a rope to the top of the tallest live palm in the stand and then tie off the rope so we could slide down the rope at an angle and look down in to the top of the hollow palm tube and check on the development of the chick inside.  Using these techniques we found that in one Blue-and-gold nest, two chicks hatched but were taken by an unknown predator about 1 month later. Another nest was less than 3 ft. deep and over the course of the season the bottom continued to rot making the hole deeper and deeper. Unfortunately, within a few days of hatching the bottom of the nest dropped out presumably killing the new chicks. In a third nest, the first clutch of eggs disappeared before hatching but the pair quickly re-laid. The two eggs from this second clutch both hatched but the older chick quickly became much larger than its younger sibling and the younger bird died within about 16 days of hatching. This older bird survived and fledged successfully. At the fourth nest this pattern was repeated, the younger chick died and the older went on to fledge. In the 5^th and final nest, only one egg hatched and this chick went on to fledge about 90 days later. So in summary, five nests started, three failed (at one of these the adults re-laid) and the other three fledged one chick each.

It was surprising to me that the dead palms last for an average of only 4 years before they fall over. Since most palms do not rot sufficiently in the first year to be useable, it suggests that the average palm may be useable for only about 3 nesting seasons. When this is combined with the fledging rate of 3 chicks per 5 nests it suggests that only about 2 chicks may fledge from each palm. The number of palms and the number of active nests I have monitored is still very small, so this figure of less than 2 chicks is just a very rough estimate. The survival figure for the palms may also be skewed by the fact that before 1998 researchers would cut holes in the sides of the palms to study and film the chicks. I am unsure how this cutting may have influenced the palms, but I do not plan to continue cutting such access holes so I can see if the palms last longer when no holes are cut.

I have no plans to cut additional palm trees in the swamp near TRC. Instead I hope to develop a new more durable artificial nest box that will last for many years. Towards this end, I have hung three nest boxes in the TRC palm swamp this year. The nest boxes are made from a piece of 12-inch diameter PVC pipe. One is 5 ft long and the other two are 8 ft long. The 12-inch diameter matches almost exactly the diameter of the palm cavities the birds are using naturally. They have a metal bottom but no top in order to imitate the open-topped palm cavities that the birds use naturally. The bottom of the box is lined with a mixture of saw dust, gravel and sand in order to provide a soft substrate on which the birds can lay their eggs. Each box is hung from a live tree at a height of about 25-45 ft. immediately adjacent to the 5 palm nests that were used in 1999-2000. It is hoped that by these structures of PVC and metal on live palms will produce young for decades. Hanging these boxes is our first step towards designing a more durable artificial alternative to dead palms. If the boxes we place this year fail to attract macaws in the 2000-2001 breeding season, we will have to go back to the drawing board and try to come up with a more elaborate free-standing nest structure that does not have to be attached to a live palm. 

This work forms part of the larger Tambopata Macaw Project. Headquartered at the Tambopata Research Center, this project is working to develop techniques to increase the reproductive output of Scarlet, Green-winged and Blue-and-gold Macaws. At TRC we are blessed with healthy populations of all three species, so the goal of our work is not to increase the local populations, but to develop techniques can be used to help populations of large macaws in other areas where they are declining or endangered.

Literature Cited

Collar, N. J. (1997). Family Psittacidae. Handbook of the Birds of the World. J. del Hoyo, A. Elliott and J. Sargatal. Barcelona, Spain, Lynx Edicions. Volume 4 Sandgrouse to Cuckoos: 280-479.

                     

Juniper, T. and M. Parr (1998). Parrots: A Guide to Parrots of the World. New Haven, Yale University Press.

        

Nycander, E., D. H. Blanco, et al. (1995). Manu and Tambopata: nesting success and techniques for increasing reproduction in wild macaws in southeastern Peru. The Large Macaws: Their Care, Breeding and Conservation. J. Abramson, B. L. Spear and J. B. Thomsen. Ft. Bragg, CA, Raintree Publications: 423-443.