The following 50 birds are the most numerous species recorded—during breeding season only—in North America over the past 30 years. They were inventoried during the yearly North American Breeding Bird Survey conducted by the U.S. Department of Fish and Wildlife and Canadian Wildlife Services. The list is arranged from most abundant to least abundant.
Despite the efforts of thousands, the list does not begin to record the actual number of birds. There are huge ups and downs in the bird count from year to year. All sorts of conditions make it approximate. There are significant changes in population based on weather. Counters get more accurate inventories in some terrains than in others. And because birds fly, they are very tricky to tally. Moreover, the count is made in June. Many species move south out of North America in the winter, and so by December the picture is dramatically different.
Understanding these highly successful birds’ relationship to Earth and to each other is tremendously interesting. On the following pages are descriptions of these birds arranged according to their taxonomic classification. The beauty of taxonomy is that it arranges families in the order in which they first appeared on Earth, and it groups together birds that have similarities. You will find that Passeriformes (perching songbirds) make up the bulk of the list, which tells us that songbirds have adapted well to our planet's present climate and habitat.
The species are preceded by a description of their family's shared attributes. Refer to the Taxonomic Classification for a description of the uniformities within each order.