Re: Green Jay, best spot for Western Tanagers
http://help.ebird.org/customer/portal/articles/1822748-ebird-review-standards
towards the bottom, click "Filter_taxa_recommendations_19Jan2016_CA.xlsx"
Things like Pin-tailed Whydah and Red-masked Parakeet, which may be established/establishing at locals levels, but don't yet fit the criteria for inclusion on the California state list, are validated in eBird. One-off, obvious escapees, regardless of how long they stick around, like, well, any flamingo in California, Burrowing Parakeet, or Gray-crowned Crane, are invalidated [or in this case Green Jay]. Somewhere in the middle of that spectrum are things like Mandarin Duck and European Goldfinch which probably aren't close to establishment, but show up with enough frequency that they are worth keeping more public tabs on, and are therefore validated.
Source: SanDiegoRegionBirding Latest Reports