Population status

Bonaparte's Gull
(Chroicocephalus philadelphia)

The Bonaparte's Gull winters widely throughout the Great Lakes south to Mexico and the Caribbean Islands (Burger and Gochfeld 2002). Christmas Bird Counts offer good coverage of those individuals wintering in temperate regions, but poorer coverage of more southerly wintering birds and the results combine data from the United States and Canada. The Breeding Bird Survey does not adequately cover the northern portion of this species' breeding range. Based on the Christmas Bird Count results for North America, the Bonaparte's Gull has increased largely in Canada, but the precision of the trend estimate is poor and the magnitude of that increase is uncertain. However, an assessment of birds in the Salish Sea, British Columbia, indicates the species experienced a decline of 4.5%/year, from 1994-2010, similar to many fish-eating birds in the region (Vilchis et al. 2015).


Picture of logo Christmas Bird Count (CBC)

Additional information on: Christmas Bird Count (CBC)

Table 1: Population trends by geographic area
Geographic areaTime PeriodAnnual trend Table 1 - footnote 1 Limits
North America1965-20122.1-1.86.7

Breeding Bird Survey (BBS) - Canadian analysis

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

Table 2: Population trends by geographic area
Geographic areaTime Period Table 2 - footnote 1 Annual trend Table 2 - footnote 2 Intervals Table 2 - footnote3
Canada Select to view graph of the geographic area: Canada 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis1970-2012-5.8-14.33.2