All flagged Warbling Vireos require audio

[Mike Thompson]

Hi everyone - We are well into the first migratory season in which Western Warbling Vireo (WEWV) and Eastern Warbling Vireo (EAWV) are treated by eBird as separate species. To help manage this split, the current Colorado eBird policy is intentionally straightforward:

1. Any flagged submission as either EAWV or WEWV must include diagnostic audio to be accepted.
2. Flagged submissions without audio must be revised to WEWV/EAWV (slash) to be accepted.

In short: if it flags, include audio.

Statewide eBird filters for EAWV and WEWV have been carefully crafted by Kathy Mihm Dunning and Andrew Spencer. The filters balance accuracy while accommodating new insights, recognizing that much remains to be learned about status and distribution. As always, filters are subject to improvement, with plans to revisit this coming winter after a full season of observations.

Areas most affected by the split and filter changes include portions of eastern Colorado, the Urban Corridor, and the Front Range.

Currently, diagnostic vocal identification relies on subtle differences in song. Colorado examples of each species can be found here:

• Western Warbling Vireo: https://media.ebird.org/catalog?birdOnly=true&taxonCode=wewvir2&mediaType=audio&sort=rating_rank_desc&view=grid&regionCode=US-CO&tag=song
• Eastern Warbling Vireo: https://media.ebird.org/catalog?birdOnly=true&taxonCode=eawvir1&mediaType=audio&sort=rating_rank_desc&view=grid&regionCode=US-CO&tag=song

Photos are also strongly encouraged, especially those clearly showing facial features and primaries. While audio is currently required for species-level confirmation of flagged submissions, this policy may relax as we gain more experience. Well-documented slash submissions, particularly those with strong photo evidence, could be candidates for retroactive upgrade.

eBirding of Warbling Vireos requires caution and restraint, and will present challenges for everyone. Thank you for your understanding and important contributions!

Mike Thompson