Heermann's Gull
(Larus heermanni)


Picture of bird
© Mike Baird - License
For additional photos and vocalizations, visit Dendroica. (Link opens in a new window.)

The entire world’s population of Heermann’s Gull breeds on just a few islands in the Gulf of California, Mexico, though there have been breeding attempts in southern California. After the breeding season, many of these birds undertake a unique "reverse" migration, heading northward up the coast of North America, as opposed to the usual southward direction of most North American migratory bird species. Most of the overwintering population occurs along the Pacific coast from Oregon to Guatemala, however a small number reach the species’ northernmost range limit in southwestern British Columbia. Heermann’s Gull is not sufficiently monitored by any survey in Canada to reliably determine changes in this small population’s status relative to 1970, but Christmas Bird Count data from the United States and other observations suggest a large increase in the continental population. It is likely that <1% of the world’s population over-winter in Canada, thus Canada’s conservation responsibility for this species is considered to be very low. This species has been identified as a priority for conservation and/or stewardship in one or more Bird Conservation Region Strategies in Canada.


Main designations for the species
DesignationStatusDateSubspecies, population
IUCN (Global)Near threatened2018 
Partners in Flight (North America)Watch list - yellow R2017 
Wild Species (Canada)Unrankable2015 
State of North America’s BirdsWatch list2016 
Bird Conservation Region StrategyPriority Species2013 

Population status

Geographic area or populationPopulation change relative to ~1970ReliabilityStatus in relation to goal
CanadaData DeficientData DeficientData Deficient

Population estimate

Geographic area or populationPopulation estimate
CanadaNot yet available

Distribution maps


Migration strategy, occurrence

Seasonal visitor

Responsibility for conservation

Geographic areaResponsibility based on % of global population
CanadaVery Low

Conservation and management

The restricted breeding range of the Heermann’s Gull in Mexico make them especially vulnerable to human and natural disturbances. Reproductive success is influenced by food availability (particularly potential competition with commercial sardine fisheries), non-native mammalian predators (black rats), and human disturbance (Velarde 1999). The large nesting colony on Isla Raza, holding over 90% of the world’s population, was designated a seabird sanctuary in 1964. This designation effectively discontinued historical egg harvests that had accounted for the removal of up to 50,000 eggs annually, and the presence of wardens and biologists likely acts to discourage other forms of human disturbance (Islam 2002). Increasing sea surface temperatures may impact the population if rates of sea surface anomalies continue to increase (Velarde and Ezcurra 2018). The colony has experienced almost complete reproductive failure in five of the past eight years; this has been attributed to overfishing and changes in the environment, which also affect food availability (BirdLife International 2018c).


Bird conservation region strategies

Environment and Climate Change Canada and partners have developed Bird Conservation Region Strategies in each of Canada’s Bird Conservation Regions (BCRs). In these strategies, selected species are identified as priorities for one or more of the following reasons:

  • conservation concerns (i.e., species vulnerable due to population size, distribution, population trend, abundance, or threats)
  • stewardship responsibilities (i.e., species that typify the regional avifauna or have a large proportion of their range or population in the sub-region)
  • management concerns (i.e., species that require ongoing management because of their socio-economic importance as game species, or because of their impacts on other species or habitats)
  • other concerns (i.e., species deemed a priority by regional experts for other reasons than those listed above or because they are listed as species at risk or concern at the provincial level)

Select any of the sub-regions below to view the BCR strategy for additional details.

BCRs, marine biogeographic units, and sub-regions in which the species is listed as a priority
RegionSub-region and priority type
Northern Pacific RainforestNorthern Pacific Rainforest, sub-region and priority type: Pacific and Yukon -- Stewardship