Map_thumbnail_large_font

Larus occidentalis

Status_ne_offStatus_dd_offStatus_lc_onStatus_nt_offStatus_vu_offStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES CHARADRIIFORMES LARIDAE

Scientific Name: Larus occidentalis
Species Authority: Audubon, 1839
Common Name(s):
English Western Gull

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Ekstrom, J., Butchart, S., Calvert, R.
Justification:
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Geographic Range [top]

Range Description: The Western Gull is found on the Pacific coast of North America, ranging from Vancouver Island (Canada) to the southern tip of Baja California (Mexico), and breeding from north-west Washington (USA) to central Baja California (del Hoyo et al. 1996).
Countries:
Native:
Canada; Mexico; United States
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population Trend: Increasing

Habitat and Ecology [top]

Habitat and Ecology: This species is essentially confined to the coast, staying on a few kilometres inland. It has a very varied diet, including marine fish and invertebrates, eggs, chicks and adults of seabirds, carrion, spawning salmon, and it may attack and kill newborn seal pups. Some males may establish feeding territories in alcid or cormorant colonies feeding mainly by predation, piracy and scavenging, occupying the same territory year after year. It also drops shellfish on to rocks to break them. It lays from late April or early May, and later in the north, nesting on barren substrates in colonies on rocky islets with some herbaceous cover and gravelly beaches. Some populations are migratory whilst others are sedentary, and individuals tend to disperse depending on food availability (del Hoyo et al. 1996).
Systems: Terrestrial; Marine

Citation: BirdLife International 2012. Larus occidentalis. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 28 November 2014.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided