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The site was identified as internationally important for bird conservation in 2021 because it was regularly supporting significant populations of the species listed below, meeting IBA criteria.

Populations meeting IBA criteria ('key species') at the site:

Species	Red List	Season (year/s of estimate)	Size	IBA criteria
Heermann's Gull Larus heermanni	NT	resident (2013)	31 individuals	B1a
Yellow-headed Amazon Amazona oratrix	EN	resident (2015)	34 individuals	A1
Mexican Parrotlet Forpus cyanopygius	NT	resident (2015)	31 individuals	B1a

Ideally the conservation status of the IBA will have been checked regularly since the site was first identified in 2021. The most recent assessment (2022) is shown below.

State (condition of the key species' habitats)
Habitat	Quantity (% remaining)	Quality (% carrying capacity)	Result
Forest	good (>90%)	good (>90%)	favourable
Marine Coastal/Supratidal	good (>90%)	good (>90%)	favourable
Shrubland	good (>90%)	good (>90%)	favourable

Pressure (threats to the key species and/or their habitats)
Threat	Timing	Scope	Severity	Result
Invasive and other problematic species and genes	happen­ing now	most of popul­ation/area (50–90%)	no deteri­oration (<1% over 3 gener­ations)	low
Climate change and severe weather	happen­ing now	few individ­uals/small area (<10%)	slow deteri­oration (1–10% over 3 gener­ations)	low
Residential and commercial development	happen­ing now	few individ­uals/small area (<10%)	no deteri­oration (<1% over 3 gener­ations)	low
Energy production and mining	happen­ing now	few individ­uals/small area (<10%)	no deteri­oration (<1% over 3 gener­ations)	low
Human intrusions and disturbance	happen­ing now	few individ­uals/small area (<10%)	no deteri­oration (<1% over 3 gener­ations)	low
Pollution	happen­ing now	few individ­uals/small area (<10%)	no deteri­oration (<1% over 3 gener­ations)	low
Transportation and service corridors	likely in long term (beyond 4 years)	few individ­uals/small area (<10%)	no deteri­oration (<1% over 3 gener­ations)	low
Agricultural expansion and intensification	past (and unlikely to return) and no longer limiting	some of popul­ation/area (10–49%)	no deteri­oration (<1% over 3 gener­ations)	low
Biological resource use	past (and unlikely to return) and no longer limiting	some of popul­ation/area (10–49%)	no deteri­oration (<1% over 3 gener­ations)	low

Response (conservation actions taken for the key species and/or their habitats)
Designation	Planning	Action	Result
Whole area of site (>90%) covered by appropriate conservation designation	A compre­hensive and appropriate manage­ment plan exists that aims to maintain or improve the popul­ations of qualify­ing bird species	The conservation measures needed for the site are being comprehensively and effectively implemented	high

Year	Protected Area	Designation (management category)	% coverage of IBA
1995	Islas del Golfo de California	UNESCO-MAB Biosphere Reserve (UA)	90
2000	Islas del Golfo de California	Área de Protección de Flora y Fauna (VI)	90
2000	Islas Marías	Reserva de la Biosfera (Ia)	64
2005	Islands and Protected Areas of the Gulf of California	World Heritage Site (natural or mixed) (UA)	100
2010	Islas Marías	UNESCO-MAB Biosphere Reserve (UA)	100

Habitat	% of IBA	Habitat detail
Forest	88	Tropical deciduous; Tropical semi-deciduous; Mangrove
Marine Neritic	8
Rocky areas (eg. inland cliffs, mountain peaks)	1	Rocky flats & barrens
Marine Coastal/Supratidal	-
Shrubland	-	Scrub

Land use	% of IBA
agriculture	3

Tenencia de la tierra: Federal.

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Recommended citation
BirdLife International (2025) Important Bird Area factsheet: Islas Marías (Mexico). Downloaded from https://datazone.birdlife.org/site/factsheet/islas-marías-iba-mexico on 08/01/2025.