The eBird database will be unavailable from 8:00 a.m. Eastern Time on November 17 until 8:00 a.m. Eastern Time on November 19. You won’t be able to enter your sightings or view checklists using the ebird.org website. You can still enter your sightings with the eBird Mobile app and submit them when eBird is back up. This article from Cornell has more information – Cornell Lab Scheduled Database Maintenance.