Population status

Violet-green Swallow
(Tachycineta thalassina)

The Breeding Bird Survey (BBS) is the most reliable survey for determining population trends in the Violet-green Swallow, although it covers only about 45% of the breeding population in Canada. BBS results indicate that the Canadian population has undergone little change since about 1970. The continental population has also changed little overall since the mid-1960s, as shown by BBS results from throughout North America. However, BBS coverage of the northern portion of the population in both countries is poor.

 

Breeding Bird Survey (BBS) - Canadian analysis

Additional information on: Breeding Bird Survey (BBS) - Canadian analysis

Table 1: Population trends by geographic area
Geographic areaTime Period Table 1 - footnote 1 Annual trend Table 1 - footnote 2 Intervals Table 1 - footnote3
LowerUpper
Canada Select to view graph of the geographic area: Canada 1973-2012; Breeding Bird Survey (BBS) - Canadian analysis1973-20120.1-1.21.5
 

Breeding Bird Survey in North America (BBS) - U.S. analyses

Additional information on: Breeding Bird Survey in North America (BBS) - U.S. analyses

Table 2: Population trends by geographic area
Geographic areaTime PeriodAnnual trend Table 2 - footnote 1 Limits
LowerUpper
North America Select to view graph of the geographic area: North America 1966-2012; Breeding Bird Survey in North America (BBS) - U.S. analyses1966-2012-0.4-10.1
 

References