What's Happening with the Keel-billed Motmot in Costa Rica?
Costa Rica is home to six species of motmots including the uncommon Keel-billed Motmot.
The double hoots of the Lesson's Motmot are commonly heard in a variety of habitats in the Central Valley and on much of the Pacific slope.
The Turquoise-browed Motmot is a common bird in most dry forest habitats.
Here's one with a Black-bellied Racer.
In humid forest habitats of the Caribbean slope, Rufous and Broad-billed Motmots are regular birds.
That leaves us with two other motmots, both of which are uncommon and local in the northern part of Costa Rica. The Tody Motmot is a secretive bird of moist forests on volcanoes whereas the Keel-billed Motmot mostly occurs in foothill rainforest habitats.
Although most motmot species are fairly common in appropriate habitat and not threatened, the Keel-billed is different. Since this little known bird seems to be rare or decidedly uncommon in many parts of its range, it has been given a conservation assessment of "Vulnerable". One step below being officially endangered, unfortunately, little is known about this species' requirements as well as the factors that affect it. Undoubtedly, as with so many other birds, habitat destruction is the main issue but even then, we still don't know exactly which types of forest are preferred by this species, at least in Costa Rica.
It definitely occurs in foothill forests but not in as many places as one might expect, perhaps because it requires some type of microhabitat. Indeed, at several sites in Costa Rica for Keel-billed Motmot, this bird occurs at the edge of the forest or in sites with advanced second growth. With that in mind, it might seem that this species should be more common but this might not be the only factor having an effect on this species.
It might also be affected by hybridization, or at least, pairing with the Broad-billed Motmot.
It might seem strange for two species with such different appearances to form pairs but hybridization also occurs in such distinct species as the Golden-winged and Blue-winged Warblers, Lazuli and Indigo Buntings, and Bullock's and Baltimore Orioles among others. As for motmots, it might also be less surprising than expected since hybridization between two very different motmot species in the Amazon has been documented, and Broad-billed and Keel-billed Motmots overlap in terms of habitat and vocalizations.
According to Juan Diego Vargas of Lifer Tours, Keel-billed Motmots pairing with Broad-billeds had been noted in the Arenal Peninsula area for several years before Keel-billeds also started being seen at lowland sites from Sarapiqui to Laguna del Lagarto. In many or perhaps all of those lowland cases, those Keel-billeds were also observed pairing with Broad-billed Motmots.
So much hybridization occurring between these two species in Costa Rica raises some good questions:
1. Are they actually the same species?- Although this requires further study, with such differences in plumage, this might not be the best answer.
2. Do they produce viable offspring?- Another that requires further study and an answer we don't yet know but since we don't observe birds that look like a blend of both motmots, the offspring are either (1) not viable, or (2) they look mostly like either full Broad-billed or full Keel-billed Motmots. Since we have been seeing more birds with Keel-billed plumage in the lowlands, could these be offspring of those hybrid pairs? This could explain why we are seeing more of this formerly strictly foothill species in the lowlands. Or, it might also be an indication of reforestation providing more areas of suitable second growth habitat possibly preferred by Keel-billed Motmots. In any case, this is yet another facet of this species that requires further research.
2. Are they only hybridizing because they sound similar and their ranges meet?
Hybridization happening only where the ranges of these two similarly sounding birds meet might be the best explanation. They could be forming pairs but having offspring that are not viable. On another note, if Keel-billed Motmots have small populations because they require an uncommon microhabitat, some might be pairing with Broad-billeds simply because they can't find another Keel-billed to mate with. Since Broad-billeds live in a variety of habitats and therefore seem to be much more common, many more Broad-billeds than Keel-billeds might be available as possible mates.
Since we have more questions than answers, for the time being, perhaps the only thing that can be definitely stated is that more research about Keel-billed Motmots is needed, especially in areas where it occurs with the Broad-billed Motmot. If such hybridization is having an impact on populations of Keel-billed Motmots, the sooner we know about this enigmatic species, the better! To raise awareness about this special bird and the hybridization situation, Lifer Tours and the Audubon Society of Indiana have donated an interpretive sign to the Arenal Volcano National Park.
On another note, Costa Rica is now open for visitors from several countries and states in the USA. To visit, certain protocols and steps have to be followed but when you get here, we will be waiting to help you experience Keel-billed Motmots and hundreds of other fantastic birds in beautiful tropical surroundings. Contact us today to talk about your trip!