I did a bird count recently at Quebrada Gonzalez with the help of my steadfast birding friend Susan. While watching tanagers feast on fruits in a nearby tree, we had a stimulating conversation with a conservation biologist and (ecologist) who has been working at La Selva since the 1970s. Although I have heard and read about the differences between the avifauna at La Selva between those days and now on many occasions, he provided us with a rare first-hand account of what birding at the famous OTS station was like then compared to the present.
Back in the 70s, when the forests of the Sarapiqui region were much less fragmented and the effects of global climate change had yet to diminish the rains, understory insectivores like Golden-crowned Spadebill, White-whiskered Puffbird, Northern Bentbill, and various antbirds and antwrens were downright common. It sounded like you couldn’t go birding there without seeing them and the lowland rainforest resounded with the whistled notes of Black-faced Antthrush. However, another aspect of La Selva birding has also greatly changed since those more forested days. Apparently, canopy flocks were also a lot more common and included the likes of White-fronted Nunbird, Scarlet-rumped Cacique, Purple-throated Fruitcrow, and other species. Although most of these species are still present as La Selva, there are few fewer individuals and some may be restricted to the back part of the property.
Whittling La Selva down to a much smaller area of lowland rainforest (due to deforestation outside the reserve) is likely the biggest culprit but other factors such as an overabundance of Collared Peccaries, diminished rains, and ag-chemicals from neighboring cultivations don’t do the forest birds any favors. Although the changes at La Selva are some of the most drastic and best documented, we also talked about the changes that have occurred at Quebrada Gonzalez.
I started birding at this foothill forest site in 1992 and have spent countless days in that dense forest since then. Were that eBird was available in those pre-online days! Otherwise, there would be lots of quantitative data to check out. Despite the lack of data, I can at least give my impressions of birding then and now at Quebrada Gonzalez. I realize that the early observations would have missed a fair number of birds but I got a pretty good handle on vocalizations there by 95 and believe that I have experienced the place on enough occasions at various times of the year to come up with some legitimate observations. These include:
Species that seem to have declined. Basically, I record fewer individuals and the following seem to have declined the most:
Great Curassow: I used to see this majestic Cracid once in a while but haven’t in several years. The area seems to be fairly well protected so I’m not sure why they don’t seem to occur or be sighted more often. Perhaps they don’t like the sound of the highway?
Crested Guan: Doesn’t seem to be as regular.
Great Black Hawk: I am convinced that this forest black-hawk has declined in many parts of Costa Rica. I used to see it on just about every visit to Quebrada and other hilly, forested sites. I haven’t seen it at Quebrada since 1996 or 1999 and my only recent sighting was at Pocosol, an area of high quality foothill forest (although I haven’t been birding in the Osa and other places where it still occurs). I wonder if its decline is related to the decrease in amphibians, a possibly important prey item.
Gray-chested Dove: I assume it still occurs but used to see this species on most visits. I don’t recall hearing it there for some time (and when it’s around, you usually at least hear it).
Great Green Macaw: Used to be a regular visitor during the wet season. Given the overall drop in numbers of this species, it’s no surprise that it shows up with less frequency.
White-tipped Sicklebill: Quebrada Gonzalez was a reliable site for this spectacular hummingbird until the large Heliconia patch it frequented was destroyed to build an outdoor classroom. When lobster claw Heliconias are in bloom, it probably occurs.
Lattice-tailed Trogon: It’s still there but there seem to be fewer in number. For example, while I used to see one or two and hear 3 or 4 on every visit, I might hear one or two nowadays.
Red-headed Barbet: Hard to say as it might be seasonal but I used to see it with higher frequency.
Yellow-eared Toucanet: Another one that’s hard to assess because it can so easily escape detection. After seeing these regularly up until 2009 or 2010, I have recorded very few.
Woodpeckers: Seems odd and I have no idea why but I definitely record fewer numbers of Black-cheeked, Cinnamon, Rufous-winged, and Pale-billed Woodpeckers. I haven’t had a Pale-billed there for some time, and the first three seem much less common (they used to be givens during the 90s).
White-flanked Antwren: I haven’t recorded this species at Quebrada in many years, it used to be regular in understory antwren flocks. Needless to say, the other species in those flocks seem to still occur with the same abundance (Checker-throated Antwren, Streak-crowned Antvireo, Sulphur-rumped Flycatcher, Ruddy-tailed Flycatcher, woodcreepers, and Tawny-faced Gnatwren).
Black-headed Antthrush: Although I only recorded this foothill specialty a few times in the past, I haven’t had it since 1999 and don’t expect to get it again.
Scale-crested Pygmy-Tyrant: I still get one or two on the ridge of the Palmas trail but used to get several all along this trail in the past.
Yellow-margined Flycatcher: Doesn’t seem to be recorded as regularly.
Golden-crowned Spadebill: I’m not sure when I last had this understory flycatcher at Quebrada but it used to be quite regular.
Boat-billed Flycatcher: I don’t record this widespread species as often as I used to.
Rufous Piha: I recall this species being regular up until 1996. I’m not sure if I have had it there since.
White-ruffed Manakin: Still regular but numbers seem much lower than in the past when it was one of the more frequently seen birds in the understory.
Stripe-breasted Wren: Same situation as the manakin. Used to be such a common bird that it was impossible to miss. Not any more although several still live in that forest.
Band-backed Wren: This arboreal wren seems to have declined in many areas. I only get one or none during a day at Quebrada when it used to be a given.
Ashy-throated Bush-Tanager: An uncommon taxon that probably deserves species status, it seems much less common at Quebrada (and was never really common on earlier visits).
Blue and gold Tanager: Same as for the bush tan.
Tanagers: I feel like there are fewer tanagers compared to the past but the difference isn’t very noticeable.
Scarlet-rumped Cacique: This species still occurs but there seem to be less. For example, the other day, I heard maybe two or three. In the past, the ringing calls of this species (along with Cinnamon and Rufous-winged Woodpeckers) were a typical, frequent part of the soundscape and I would see several caciques during a day of birding.
Not to mention, various edge species that have disappeared as the forest on the other side of the road has grown up.
Birds that occur there now but weren’t recorded in the past. These are probably moving upslope:
Slaty-tailed Trogon: It shows up once in while but I never had it during the 90s. Possibly moving upslope and maybe even replacing Lattice-tailed.
Streak-chested Antpitta: This formerly absent species is now recorded on most visits (had at least three heard on the day of the count).
Black-faced Antthrush: Never had this lowland species in the past, now it is regular on the Ceiba and Botarrama trails.
Birds that should seemingly be there but don’t seem to be present or more common:
Slaty-breasted and Great Tinamou: Not sure why these aren’t more common. They occur but seem to be very few in number. Or, perhaps they don’t call as often?
White-fronted Nunbird and Rufous-tailed Jacamar: These have never been recorded at Quebrada as far as I know. The soil may differ from forests of the same elevation in the Tilaran Mountains where these species occur and this makes me wonder if it plays a role in limiting their burrow nesting behavior. However, other burrow nesters such as White-whiskered Puffbird, and Broad-billed and Rufous Motmots occur so who knows.
Lanceolated Monklet: There are rumors that this very rare bird was recorded in the past but I have yet to find it at Quebrada (and I can’t help but whistle like one on most visits, a strategy that has worked in Ecuador).
Keel-billed Toucan: Nope, don’t know why I don’t see it more often.
Leaftosser species: While others have possibly recorded Tawny-throated on one occasion, I have heard nary a chip note from any Sclererus at Quebrada.
Red-capped Manakin: I have very rarely had this bird at Quebrada but still get them on most visits just up the road at El Tapir.
Thrush-like Schiffornis: Another one at El Tapir and rarely heard on the back part of the Palmas loop.
Song Wren: Same deal as the Schiffornis.
Like I said, I wish I had quantitative data because I record fewer numbers of several species, there seems to be less fruit in the understory, and the forest looks drier than it used to. Thinking about this makes me want to go back, do a bunch of surveys and try to figure out what’s going on in one of my favorite birding locations anywhere.