Back from a busy three weeks in the field. October is usually our busiest month in terms of monitoring nests and this year is no exception. We are currently following the progress of four nests, three of which have chicks and one that is incubating. I spent my time at 7 islas where amazingly all three BTM pairs were nesting this month, the surprise being the last pair. We refer to them as the vaca muerta (dead cow) pair because their nest is in a forest island that has a cow carcass 30 meters from our blind. I thought this pair were young birds ‘playing house’ in a curupau tree cavity. Lo and behold the female began incubating in early October. We kept an eye on it as we’d seen Toco toucans (the scourge of BTM nests, predating both eggs and small nestlings) in this island. For three weeks we never witnessed an attack on this nest. It was hard to imagine anything getting into this nest as the entrance was so narrow. The narrowest we’ve seen yet, a little over 8 cm (3 in) at its widest point. The pair has to enter it sideways.
One of our crew left the blind at dusk on the 16th. When another worker returned to the nest early the next morning, the behavior of the nesting pair had changed radically. The female was out of the nest and appeared agitated. When she entered the nest cavity it was only briefly. She even went inside another nest by our blind where I’d seen Golden-collared macaws guarding the past week.
We inspected the curupau nest the next day to confirm that the nest had been predated. How something frightened the female off the nest and slip through the narrow entrance still baffles me. Given the length of a Toco’s bill (around 20cm, 8in) it’s not impossible to imagine them getting their head and bill through the hole to extend down and get to the eggs.
One nest the Tocos tried to predate but didn’t succeed in doing is still going strong. This nest had two eggs which hatched two chicks. When the nestlings were less than a week old a pair of toucans would regularly appear in this island before sunrise make it necessary for us to leave camp when it was still dark to get to the nest on time. One morning a toucan actually flew directly into to the nest entrance. Luckily one of our field team was there to quickly exit the blind, frantically waving his arms and yelling to scare the toucan off the nest. On three other occasions we had close calls such as this. It’s a credit to the dedication of our crew that we would get to this nest pre-dawn for a period of three weeks until the chicks grew too large for toucans to predate (around 300g).
Using a digital camera with a decent optical zoom, I’ve been able to photograph the facial feather lines of this pair and confirm that they nested in an adjacent island in 2004. This pair fledged one chick in that year and look to be in good shape to fledge two in 2006. Thanks to the Canadian branch of WPT for purchasing the camera as it allows me to rapidly and reliably ID BTMs in the field (without having to trap and bands adults).
The second nest with a chick in this area is the totai palm snag, nest 24. Recall that this nest lost the first nestling that hatched late September. We still don’t know if it was predated or died in the first few days and was subsequently removed by the nesting pair. Due to these uncertainties we put a 12-hour watch on this nest to better protect the remaining two unhatched eggs. This meant from dawn until dusk someone was in the blind monitoring this nest. In the end this nest only hatched one nestling, the last egg being infertile. Although we didn’t observe any predation attempts on this nest, the nest tree itself keeps us on guard. During one storm the upper third of the snag actually snapped off. The remaining portion of the trunk that constitutes the nest cavity is extremely brittle so we’ve added strips of light-weight wire around this area to add support and prevent the cavity from splitting open. We’ve kept an extra nest box by this nest in the event that the cavity (or nest tree) collapses. If this were to happen we can transfer the chick to the box. Squawks and calls from the nestling will lead the nesting pair into the box to feed it. Hopefully the nest tree will hold up until late December when the chick will fledged (though nothing is a given with this species).
While it was disappointing to lose the vaca muerta nest I received a pleasant surprise before I left the field. The tree cavity we removed the bee hive from in early September is now an active BTM nest. The pair at this nest is the same pair that fledged a single chick in the area in late January 2006. When we started this field season in August we saw no signs of this chick so presumably it didn’t survive and the nesting pair is giving it another go. The great thing about this nest is that it is a four-minute walk from the ranch house we stay at. In other words we should be able to get to the blind pre-dawn to ensure that toucans don’t dine on BTM eggs.
My exit from the 7 islas area was an adventure (to say the least). Heavy rainfall mid-Oct washed away a bridge on our direct route back to Trinidad. We were forced to take a longer trip in extremely muddy conditions, turning what is normally a six hour drive into a three day odyssey. The truck got stuck on four occasions including one nasty affair that took us four hours to get out of.
Despite all the stress of this trip I was simply relieved to get the truck out of this area. One rancher I talked to decided to leave his truck there until next June when the water subsides. Any future trips we make into the 7 islas area will be by small plane as the land route is effectively cut off. The landscape is officially flooded.
An unexpected twist to this story is that by being forced to take a longer route we passed through a town I’ve never been to. We rested there for a day to recover from all the toiling in the mud the previous day. Of course we drew attention to ourselves driving around in a muddy white truck with a six-meter ladder attached to it. When I explained to a local what we were up to he recommended that I look up an ex-macaw trapper who was active in the area in the ‘70s and ‘80s. Sure enough I found him and it was extremely interesting to talk with him on numerous fronts. Other ex-trappers had told me that BTMs were always rarer than the two larger macaw species in the Llanos de Moxos (Blue-and-Gold Macaws; BGMs and Green-winged Macaws; GWMs). Not so according to this guy. He told me of a clay lick where he’d see groups of BTMs, BGMs and GWMs visit in equal numbers, usually exclusive from one another. This claim is interesting as it is the first account I’ve heard of BTMs consuming clay and the idea that BTM’ numbers can be equal to those of BGM’s is not a pipe dream. At present BGMs outnumber BTMs by a factor of 6:1. Turning the tide so that these numbers become more balanced overtime is thus a realistic goal for this project. The trick to this is getting more BTM chicks into the wild than BGMs are fledging. Nest boxes may help here provided they don’t permit BGMs from using them. Our nest boxes have received little attention from BTMs and lots of attention from BGMs. On one occasion I saw six BGMs perched around a nest box, the entrance to which had been heavily bitten at. PIC In fact almost all of our boxes have evidence of damage, likely by BGMs. We’ve yet to actually a BGM actually inside a box, so for the time being it appears that the metal plates we placed over the nest entrance are working. BGMs tend to nest later than BTMs though (starting in Nov/Dec.) so time will tell if our boxes hold up to the BTM’s beaks.
The other bonus of our unexpected stay in this town was that I finally got to see Red-shouldered Macaws Diopsittaca noblis. This is the smallest macaw species and for unknown reasons is not found where we work with BTMs. I’ve been lucky enough to see all the extent species of macaw in the wild now save Blue-headed Macaws Propyrrhura couloni. Unfortunately if I want to see Spix’s Macaw Cyanopsitta spixii, my best bet is in the Sao Paulo zoo. The species went extinct in the wild in 2000, making Blue-throats the most endangered species of macaw in the wild. The buck stops here though. We’re determined to not lose the last wild Blue-throats.
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