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Nest 20 predated

by Toa Kyle

We've lost nest 20 to predation. I mentioned before that when a chick is over 300g its predation risk is lowered. Nest 20 has proved to be an exception. One of our crew went to check on this nest the other morning to find a distressed nesting pair and numerous vultures circling above the nest. When he inspected the nest cavity, only portions of the nestling's head and feet remained. This chick had to be well over 400g when it was predated. I back to wondering if a Great-horned Owl is responsible.

Whenever we lose a BTM nest I'm left wondering if I could have done more to prevent it from happening. This particular nest had an open crown. By installing light weight roofing, we could have better protected the nestling by shielding it from predators that fly overhead and limiting access to the nest cavity itself. We discussed doing this when we first discovered the nest but had misgivings about attempting to do so due to the flimsy nature of the upper portion of the nest. In the end we decided not to take the risk of the nest cavity collapsing due to the extra weight added by roofing. In retrospect I wish we'd experimented with something. Losing a BTM nest always stings a bit. We put up a nest box in this island with the hope that the pair will take to it the next breeding season. They'd already invested two months in this year's nest (one month incubating and one month caring for a nestling) so it's unlikely they'll nest again this season.

We also put up a box in the island where we'd seen t the wounded female a week ago. She was around with her mate and showed no visible signs of injury. The pair has shown no interest in the snag they were excavating in October. I'd be surprised if they did up nesting after seeing the female in such a bad state recently.

Something interesting happened while I was up in the ropes installing the nest box. There was a pair of BGMs perched around 30m me, chatting with other parrots in the forest island. In a flash a Southern Caracara Polyborus plancus dove in from nowhere, taking a swipe at the BGMs.

The attack was unsuccessful but totally surprised me. On one hand it's rare to actually witness a predation attempt and on the other, I didn't know that Southern Caracaras were potential predators of adult macaws. Normally I'd seen this species feeding on motacu fruits or hanging out with vultures at cow carcasses. That some individual caracaras go after large macaws may explain some of the macaw remains we've found throughout the course of the project. This species is abundant where BTMs are found. I suspect that preying on macaws is not an inherent trait for caracaras rather that some individuals do it opportunistically. We may have to look at predator control (ok, a euphemism for shooting predators) on a case by case basis. Both Southern Caracaras and Great-horned Owls have large distributions and are not threatened where BTMs are found. We simply can't allow these species to feed on the few remaining BTMs in the wild.

Having lost nest 20, I shifted our attention to the southern BTMs. There's an estimated 25 BTMs one hour south of Trinidad. For unknown reasons this subpopulation tends to breed later than the northern birds, usually around the same time as BGMs. I'd like to work with at least one more nest this season so the south may be my best bet.

One regretable trend happening in the south right now involves a nest box program for BTMs initiated by Armonia, another NGO working with the species. Last year the put up 20 boxes in the area, the majority of which were occupied by BGMs (75% of all boxes). Clearly something had to be done with the entrances to these boxes to exclude BGMs but allow smaller BTMs to enter. Alas, no changes were made and of the four boxes I saw at a ranch we work at, all were occupied by BGMs, two of which are incubating. The last thing we need in this area is more BGMs chicks fledging. BGMs compete with BTMs for nest sites and resources. Due to their larger size they usually win most confrontations. Being superior in numbers doesn't hurt their overall success either. In past years at this particular ranch I could regularly see a BTM pair around the house. Not so this season. Unfortunately three of the nest boxes occupied by BGMs are in close vicinity of the house. On several occasions I've seen these pairs aggressively defend the area around their nest box from other macaw pairs that fly too close. Presumably the BTM pair that formerly inhabited this area received the same treatment. By bringing this up I don't mean to criticize Armonia's actions rather point out again the need to learn from the mistakes of past field seasons and fix them for the future.

Posted by Toa Kyle on 11/23 at 12:12 PM
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A wounded female and possible siblicide

by Toa Kyle

I'm back in town after checking on nest 20 (the new nest we discovered late October). The nestling is progressing fine. It weighed in over 300g at around 17 days of age. It's always a relief when a chick gets to this size as it's highly unlikely med-sized predators such as toucans and Crane-hawks can predate nestlings of this size. The location of this nest is a bit odd as there are few other macaw species around and we've yet to see any potential nest predators around. This chicks still has along way to go though prior to fledging (nine weeks in fact).

We're banding all the nestlings we find this season. This is the first time we've banded. It'll help us track chick survival after the first year in the wild and also help us trace any birds that may show up in the illegal bird trade. We slip bands on around 10 days of age, allowing birds to 'grow' in them. Once fully grown it is impossible to remove a leg band.

We received quite a scare from another potential nesting pair in this area. This pair had been excavating a motacu palm snag we'd carved a cavity into in 2002. Since 2004 a pair was regularly seen guarding the cavity during the nesting season though with no chicks to show for it. The upper part of the snag (containing the nest) fell over but the pair excavated a new cavity directly below where the old one broke off. I went to check on this pair a few days ago and took my first photos of this pair. To my horror the female was bleeding profusely in the neck and breast area.





She didn't appear to have problems flying but to see a bird in distress like that was troubling. It returns us to the unresolved question of what animal is predating adult BTMs. A more disturbing explanation for the cause of this female's injury relates to when we saw her like this and the area she inhabits. There are many lakes in this region and people from the city come here to fish on Sundays (I should add that at this particular ranch they are doing so illegally, though there is little enforcement here). Last year, at the side of a lake I found the remains of a Blue-and-Gold Macaw stuffed into a tree cavity with a bag of salt. Someone had actually shot the bird for fish bait. While I can understand the factors that drive people to trap macaws for the pet trade it's hard to accept killing them to catch fish. We'll be keeping an eye on the island where we regularly see the injured female and her mate to see if she pulls through. In the event that we don't see her anymore, we'll search for her remains. Hopefully there won't be a lead slug in it.

More bad news to relay (so goes BTM conservation at times). The second chick of nest 27 was found dead in the nest during an inspection last week. It was almost seven weeks old (and only a month from fledging). This is a perplexing as there were no obvious wounds on the bird. It was growing normally and had a full crop when it was discovered dead. The only clue which may explain its death lies in the manner in which its remains were found. It was partially buried in the nest litter with the first (and larger) chick sitting on top of it. This may be an extreme case of nestling rivalry where the older chick may have killed its nest mate possibly by suffocating it. Whether this happened accidentally or intentionally we don't know but to lose an otherwise healthy chick at this stage of development is truly sad.

On a positive note the 'bee-hive' nest hatched two chicks the other day. This brings us up to seven chicks but we've lost five nestlings along the way. With each passing field season the bar is continually raised with respect to what more needs to be done for the recovery of BTMs in the wild. This year the theme is nestling mortality. At least three chicks have died in the first few days of life due to neglect from their parents (ie. starvation). Another nestling lost possibly to siblicide. A goal for next season is to prepare ourselves to raise third (and possibly second) hatched chicks in captivity for later release. This will take a lot of preparation in terms of having hygienic conditions and suitable release sites but given that every wild BTM chick that hatches is so important the species' recovery, we need to do more to assist more of them through to fledging.

Posted by Toa Kyle on 11/11 at 11:56 AM
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Another nest, more starving nestlings

by Toa Kyle

We've located our sixth active nest for the season though it comes with a certain melancholy. This nest was active in 2005 too but failed due to flooding (yet another low quality open crown motacu snag). That a pair would return to this low quality nest in 2006 is curious but old habits die hard I suppose. I'd hoped to get to this particular area in September but due to work with active nests in other areas we couldn't get here until late October. I was happy to see a pair of BTM at this nest upon our first arrival but was concerned the nest could flood again. Their behavior didn't clearly show that it was active. It obviously wasn't being incubated or we'd have seen the female inside the cavity almost constantly. The pair would take brief turns entering the cavity though for short bouts. I decided on the next morning to climb with the aim of putting in a drain hole. To my surprise saw three young nestlings, one recently hatched. Going back to our experience in mid-September with nest 28 I knew we likely had to supplement the third hatched chick to keep it alive. We returned in the afternoon to supplement feed and tragically found both the second and third chick dead. Both had empty crops. The first hatched chick was obviously receiving all the meals but whether this was due to parental preference or sibling rivalry is unknown. While losing the third hatched nestling may be the norm, losing the second chick without giving it a fighting chance for survival was hard to accept. I can't help but think that if we'd arrived a few days earlier we may have been able to prevent its loss. Nevertheless a new nest with a nestling inside is good news for this season. Including this nest, we're currently monitoring the progress of six nestlings. Given how few BTMs we know of in the wild, to fledge six chicks will be quite an accomplishment plus we've still got the ex-bee hive nest to hatch chicks in less than two weeks.

I've received some bad news by radio from our NW camp. They've found the remains of a BTM. Its feathers were all over the place thus making it likely it was predated. The question is, by what? At this stage I'm inclined to think a Great-horned Owl (GHO) was the culprit. They're found at almost every site we work with BTMs at. Friends in Brazil tell me that in the Pantanal, Hyacinth Macaws become very agitated when GHO are in the vicinity of their roosts. If GHOs can predate the largest flying parrot they won't have problems with BTMs, where females can be half the weight of Hyacinths.

This is the second time we've found the remains of a BTM, a constant reminder that as we work to increase the number of BTM chicks entering the wild, adult and juvenile birds continue to exit the population via predation, disease and old age. Losing adults is always tough because macaws are in general, long-lived birds capable of producing numerous offspring in their lifetime. We still don't know if an individual that loses its mate will pair up again with time. It doesn't help matters that there's so few potential mates to choose from.

Posted by Toa Kyle on 11/03 at 11:50 AM
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A busy October

by Toa Kyle

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.

Posted by Toa Kyle on 10/21 at 11:36 AM
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