Rare bird alert

A rare bird alert (RBA) is a system for collecting and disseminating information about sightings of uncommon or unexpected bird species, usually specific to a particular region. Birders are known for sharing information with each other about the locations of unusual birds for recreation, documentation, or competition, and have used a variety of technologies to do so. Starting in the 1950s, telephone hotlines centralized reports using answering machines, replacing calling trees and becoming an important part of birding culture. Well over a hundred such lines operated in North America by the end of the 20th century. The internet, and especially eBird and social media platforms, largely replaced telephone systems in the 21st century, enabling real-time sharing with geographic precision. The speed and reach of internet-based alerts made birds and birding more accessible to the public, but have also led to controversy for the way they can draw crowds that may harass the birds.