High up in the emerald embrace of the Costa Rican rainforest, a flit of movement catches your eye. A flash of yellow darts between the leaves, alighting briefly on a branch before disappearing once more. This could be the dazzling Yellow-margined Flycatcher, a resident acrobat of the upper canopy.
The Yellow-margined Flycatcher, also known as the Yellow-winged Flycatcher or Zimmer’s Flatbill (depending on its location), is a captivating insectivore gracing our mountain forests. Though not the easiest to spot, with a bit of patience and an attentive ear, you might be lucky enough to encounter this feathered gem.
A Master of Camouflage
Standing at a mere 5 inches tall, the Yellow-margined Flycatcher is a master of disguise. Its upper body is cloaked in a cool, greenish-yellow plumage, blending seamlessly with the dappled sunlight filtering through the leaves. The underparts are a touch lighter, creating a subtle contrast.
But the true giveaway of this flycatcher lies in its wings. Each flight feather is edged with a vibrant flash of yellow, a signature feature that justifies its name. However, these bright borders are relatively narrow and only truly visible when the bird is in flight or spreads its wings.
A Life Amongst the Leaves
The Yellow-margined Flycatcher is a true denizen of the rainforest canopy. Perched high on a hidden branch, it scans the world below with its dark brown eyes, ever vigilant for a tasty insect snack. Unlike some flycatchers who actively hunt their prey, the Yellow-margined Flycatcher prefers a “sit-and-wait” approach.
Patient and focused, it waits for an unsuspecting insect to flit by, then with a lightning-fast dart, snatches it mid-air. Its wide, slightly flattened bill – a characteristic of the “flatbill” subfamily – is perfectly designed for scooping up these tiny morsels.
A Song of the Mountains
While spotting the Yellow-margined Flycatcher can be a challenge, its voice might be your best bet for detection. Their song is a series of clear, rising whistles, often described as having a nasal quality. In some parts of Costa Rica, their calls can even sound buzzy, adding another layer of intrigue to their identification.
A Species in Transition
Interestingly, the Yellow-margined Flycatcher is currently undergoing a taxonomic shift. The populations found west of the Andes mountains in Costa Rica and neighboring countries are now considered a separate species – the Yellow-winged Flycatcher (Tolmomyias flavotectus). The birds east of the Andes retain the scientific name Tolmomyias assimilis and the common name Yellow-margined Flycatcher (or Zimmer’s Flatbill).
A Glimpse into the Rainforest Canopy
Whether you encounter the Yellow-winged Flycatcher or the Yellow-margined Flycatcher here in our Costa Rican mountains, a sighting of this elusive bird is a true treat. It’s a reminder of the hidden wonders that thrive in the lush rainforest canopy, a world waiting to be explored by the curious naturalist.
Keep your eyes peeled, listen for the rising whistles, and you might just catch a glimpse of this dazzling denizen of the Costa Rican mountains!
For more information, please view our comprehensive guide about the birds of Costa Rica
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