What is the habitat of the Xantus’s hummingbird?

The Xantus’s hummingbird (Basilinna xantusii) is a small hummingbird that is native to the Baja California Peninsula and adjacent islands in Mexico. This species has very specific habitat requirements and is only found in certain areas within its narrow range.

Geographic Range

The Xantus’s hummingbird is endemic to the Baja California Peninsula in northwestern Mexico. Its breeding range is restricted to the southern half of the peninsula, from around El Rosario south to Cabo San Lucas and San José del Cabo. The species also breeds on several offshore islands in the Gulf of California, including Isla Espíritu Santo, Isla Partida, and Isla San Francisco.

During the non-breeding season, some individuals migrate north on the peninsula as far north as El Rosario. But most of the population is resident year-round in the southern part of the peninsula and on the islands.

The Xantus’s hummingbird has an extremely small geographic range, breeding in an area of only about 15,000 square miles on the Baja Peninsula and surrounding islands. This limited range makes the species vulnerable to habitat loss and climate change.

Habitat

The Xantus’s hummingbird is found in desert and semi-desert environments in its narrow range. Its breeding habitat consists of arid scrublands, tropical deciduous forests, and palm oases. Some key habitat features include:

• Desert scrub – The desert scrub habitat consists of xeric, arid vegetation such as cacti, ocotillo, brittle bush, creosote bush, and other desert-adapted plants. This habitat occurs at low elevations near the coast.
• Tropical deciduous forest – In tropical deciduous forest areas, the Xantus’s hummingbird inhabits canyons and arroyos with trees like copalquin, mesquite, and elephant tree. Dense vegetation and shade are important.
• Oases – Palm oases with fan palms, fruiting trees, and a water source are critical for this species in desert environments.
• Nectar plants – Abundant nectar plants, especially agaves and ocotillo, are required for foraging.

Some key differences between mainland and island habitat:

• Mainland – More extensive tropical deciduous forest habitat occurs on the mainland, especially in canyon areas with more water availability.
• Islands – Island habitats are drier with more desert scrub, less vegetation density, and fewer trees.

Vegetation

The Xantus’s hummingbird is highly dependent on the plant community composition of its habitat. This species gets most of its food from nectar, and it has adaptations like a curved bill and long tongue to feed from flowering plants.

Some key plant species that provide food sources and other resources for the Xantus’s hummingbird include:

• Agaves – Agaves are a critical nectar source. Species like Agave shawii and Agave vizcainoensis flower at different times to provide year-round food.
• Ocotillo – The flowering spikes of ocotillo (Fouquieria splendens) produce abundant nectar.
• Trees – Trees like copalquin (Bursera microphylla), elephant tree (Bursera microphylla), and torchwood (Bursera hindsiana) provide nectar from their flowers.
• Fan palms – Palm oases with Mexican fan palms (Washingtonia robusta) are important sources of food and shelter.
• Spring wildflowers – Wildflowers like poppy, chuparosa, and paintbrush provide supplementary nectar.
• Fruiting plants – The hummingbird sometimes eats small insects and feeds at blooming plants like prickly pear cactus for fruit sugar.

Sufficient densities of its core nectar plants allow the Xantus’s hummingbird to meet its high metabolic needs. The availability of food plants also determines breeding habitat suitability and nest site selection.

Elevation

The Xantus’s hummingbird is found at low elevations within its Baja California range. On the mainland, it occurs primarily at elevations below 1,000 meters in desert and tropical deciduous forest habitats. On islands like Espíritu Santo, the species has been recorded up to 1,400 meters in very arid habitat.

Some details on elevation limits:

• Mainland elevation range – Sea level to 1,000 meters, primarily below 500 meters.
• Island elevation range – Sea level to 1,400 meters.
• Breeding range elevation – Below 500 meters.
• Migration range elevation – Sea level to 1,000 meters.

Higher elevation areas lack the arid tropical habitats preferred by the species. Within its narrow elevation range, concentrations of agave and other nectar plants are key habitat requirements.

Climate

The climate across the range of the Xantus’s hummingbird is extremely arid, with very low rainfall. The Baja California Peninsula has a desert climate characterized by high temperatures and drought.

Some key climate features:

• Low rainfall – Average annual rainfall below 300 mm.
• Rainy summers – Rainfall concentrated in summer and early fall.
• Extreme temperatures – Summer highs above 104°F and winter lows below freezing.
• Dry winters – Little or no rainfall from November to April.

This dry desert climate means water sources like springs, oases, and arroyos are especially important habitat components. The species likely relies on moisture from nectar and fruit when water itself is scarce.

Geology and Soils

The arid habitats of the Xantus’s hummingbird occur primarily on igneous and metamorphic substrates. Shallow, rocky soils characterize much of the Baja Peninsula:

• Igneous rocks – Granite, rhyolite, andesite, basalt
• Metamorphic rocks – Schist, gneiss
• Sedimentary rocks – Some sandstone and conglomerate deposits
• Soils – Shallow, rocky soils; low organic content

In foothill and canyon areas, deeper alluvial soils allow more extensive vegetation growth like tropical deciduous forest. Soil moisture here supports denser plant cover and flowering.

Threats and Conservation

The small range and specific habitat needs of the Xantus’s hummingbird make it vulnerable to various threats:

• Habitat loss – Development, grazing, agriculture, and other human pressures reduce scrub habitat.
• Invasive species – Introduced plants, bees, ants, and other nonnatives degrade native vegetation.
• Climate change – Projected drying trends may reduce food plants and oases.
• Wildfire – More frequent wildfires could exceed native regeneration rates.

Conservation actions to protect the species include:

• Protected areas – Parts of the range are within protected natural areas.
• Habitat restoration – Removing invasives and revegetating with natives.
• Environmental water – Protecting water sources like springs and seeps.
• Wildfire management – Prescribed burns and fuel reduction to protect habitat.
• More research – Improved understanding of ecology and habitat modeling to guide conservation.

Summary

The Xantus’s hummingbird has very specific habitat needs to support its nectar-based diet and survival in an arid climate:

• Desert scrub and tropical deciduous forest vegetation with agaves and other flowering plants
• Palm oases and riparian vegetation that provide water
• Low elevation arid habitats up to 1,000 meters elevation
• Hot, dry climate with rainfall concentrated in summer
• Shallow, rocky soils

Conservation of this rare and range-restricted hummingbird requires maintenance of natural desert vegetation communities and water sources in the northern Baja Peninsula and associated islands.

Conclusion

In conclusion, the Xantus’s hummingbird is a highly specialized species adapted to arid habitats in the Baja California Peninsula. It is restricted to a narrow geographic range and specific combination of vegetation, climate, and geology. Within this limited suitable habitat, it relies on concentrations of its core food plants like agaves and ocotillo. Protection of remaining desert scrub, tropical deciduous forest, riparian vegetation, and palm oases will be crucial for conserving this unique hummingbird into the future. Careful habitat management and restoration to provide key resources like sufficient nectar sources, vegetation cover, and water availability are needed, especially in the context of expanding human development and climate change impacts. The precarious state of the Xantus’s hummingbird highlights the vulnerability of species with small ranges and ecologically constrained habitat requirements.

Here is an example table for the Xantus’s hummingbird habitat:

Nectar Sources

Here are some of the key nectar plants used by the Xantus’s hummingbird:

Having a diversity of nectar sources flowering at different times allows the hummingbird to meet its food needs throughout the year.

Baja Peninsula Climate Averages

The arid climate of the Baja Peninsula is characterized by hot, dry conditions.

The minimal rainfall, extremely high summer temperatures, and moderate winter lows create an arid climate regime.

Xantus’s Hummingbird Breeding Range

This table summarizes the breeding range extent of the Xantus’s hummingbird in the Baja Peninsula and associated islands.

The species has an extremely limited breeding distribution, making up its global population. This small range makes the hummingbird vulnerable to habitat changes.