Mixed flock…bird wave…sudden bird bonanza. Three terms for the same wonderful situation but be forewarned; this birding experience may leave you speechless, it might leave you stunned and when birding in Costa Rica, you can expect it.
Personally, I prefer the term “mixed flock”. I don’t know why, I must have read it somewhere, it’s just what I have always called it. To be clear, this esteemed birding situation is when several species are seen flocking and foraging together. Contraringly, a mixed flock is NOT when birds come in to a pygmy-owl call and not when you see a few different heron species in the same part of the Tarcoles River. It IS when a bunch of tanagers convene on a fruiting tree and ESPECIALLY when those same tanagers are seemingly accompanied by a few woodcreepers, antwrens, flycatchers, and other birds.
After many a quiet minute stalking though the rainforest, a mixed flock is a welcome burst of birding excitement, your chance to see one new bird after another in quick succession. If it happens during your only visit to a particular habitat or site, that mixed flock can also act as your one big break, your main chance at seeing a satisfying bunch of birds. The birding challenge is real but don’t panic! Keep calm, be quick with the binos and try these tips:
Mixed Flocks can Happen Anywhere but the Mega Flocks are in Mature Humid Forest
Some may dispute this statement but I stand by it. Yes, mature second growth can also entertain with groups of flocking birds and I have seen forest edge in the Caribbean lowlands doing the avian bounce but then again, that particular edge was the border of a large area of mature rainforest. I doubt there would have been as much variety in a smaller patch of woods.
When it comes down to it, remember that while birding tropical forest habitats, although you may find a mixed flock in second growth, you’ll find a lot more birds in large areas of mature forest. The higher degree of complexity generated by massive trees, vines tangles and profuse vegetation translates to a higher variety of specie and when they flock together, the result can make for some life goal birding madness.
The mega mixed flocks of Costa Rica can’t compare with those of the Amazon but I’ve seen a few that come close; notably in foothill rainforests birding on the Manuel Brenes Road, in the Osa Peninsula, and a couple other places. The mega mixed flock is a good thing to keep in mind while walking through quiet mature forest. Be ready for it because, at some point, the birding will pick up and things could get giddy.
Follow the Flock
A mixed flock doesn’t just move through and that’s all she wrote. They can and do move fast but at some point, the birds will slow down and work that forest, work it to the bone.
Like a classic house track, mixed flocks don’t stop moving. You gotta keep up, find the mixed flock groove, and you will eventually catch that Sharpbill, see most of the birds. Listen for the flock, try to find it and then stay with the birds as long as you can. But don’t leave the trail, potential hidden vipers and getting lost aren’t worth it.
Know the Flock Leaders Before You Go Birding
Even birds have leaders, choice birds followed for survivalist reasons. Anthropomorphisms aside, there are certain vocal species that act as nucleous species of a flock. Know what they sound like and you will find the flock. It also pays to know what they look like but since hearing birds is everything in the tropical forest, it pays to learn their calls.
In Costa Rica, the erstwhile mixed flock leader of foothill rainforest (and lowland rainforest of the Pacific slope) is the White-throated Shrike-Tanager. This stand out oriole-looking, flycatcher-like tanager is so associated with big mixed flocks, it deserves an invisible crown. Find it in mature forest and you will find birds. But be prepared, on some lucky days, there could be a mind-blowing bonanza of avian life being led by this bird wave king/queen combination.
In Caribbean lowland rainforest, I’m not sure if there is similar royalty but there are noisy species that often occur with other birds. A couple of the stand outs are Black-faced Grosbeak and White-shouldered Tanager.
Up in the middle elevation cloud forest, mixed flocks are fairly common and can come in many sizes. Keep checking the Common Chlorospingus and listen and look for mixed flock standards like Lineated Foliage-gleaner and Spotted Woodcreeper.
In the high elevations, check the groups of Sooty-capped Chlorospingus and listen for the likes of Yellow-thighed Brushfinch and Buffy Tuftedcheek.
Take Notes and Look at Field Guides After Watching the Flock
If I was limited to mentioning just one tip, it would be this one. No matter how well or little you know the birds creeping up branches and flitting in the foliage, whatever you do, do not stop watching them to look in a field guide. The same goes for taking written notes. I know, the temptation is real but so are the consequences and those would be missed birds.
A mixed flock in tropical forest won’t behave like birds back home (unless your birds come in quick moving groups of a dozen or more species that can move on past in nearly every level of a dense forest with a tall canopy). When a flock appears, if you don’t stay focused and try to see as much as possible, if you take eyes off the bird action to look up one or two birds in a field guide, the other 20 will likely move right on out of view. Try to see as much as you can, keep looking, and take mential notes. After the birds have moved out of reach and the forest has gone back to being humid and seemingly unreasonably quiet, that is the time to jot down notes and check out your field guides to the birds of Costa Rica.
Mixed flock action is waiting in Costa Rica. To learn more about birding mixed flocks, the best places to experience them, where to go birding in Costa Rica and more, support this blog by getting How to See, Find, and Identify Birds in Costa Rica, a 700 plus page companion for birding this beautiful country. As always, I hope to see you here!