American Bald Eagle vs Concentric Boulder Lichen

Haliaeetus leucocephalus compared with Porpidia crustulata

Key Differences

American Bald Eagle is Not Evaluated while Concentric Boulder Lichen is Vulnerable.

Taxonomic Classification

Rank	American Bald Eagle	Concentric Boulder Lichen
Kingdom	Animalia (Animals)	Fungi (Fungi)
Phylum	Chordata (Chordates)	Ascomycota (Sac Fungi)
Class	Aves (Birds)	Lecanoromycetes (Lecanoromycetes)
Order	Accipitriformes (Hawks & Eagles)	Lecideales (Lecideales)
Family	Accipitridae (Hawks & Eagles)	Lecideaceae
Genus	Haliaeetus (Sea Eagles)	Porpidia
Species	Haliaeetus leucocephalus	Porpidia crustulata

Conservation Status

American Bald Eagle

NE — Not Evaluated

Population: ~316.7K

Trend: Increasing ↑

Concentric Boulder Lichen

VU — Vulnerable

Physical Characteristics

Attribute	American Bald Eagle	Concentric Boulder Lichen
Diet	Carnivore	—
Average Lifespan	28 years	—
Average Length	90 cm	—
Average Weight	5.0 kg	—

Habitat & Geographic Range

American Bald Eagle

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, tropical and subtropical dry broadleaf forests, and flooded grasslands and savannas, among 10 distinct biome types spanning the Neotropic and Palearctic realms. Populations are also found in montane and highland environments at higher elevations.

Range

Widely distributed across Europe (8 countries), North America (United States), and South America (Ecuador).

Concentric Boulder Lichen

Habitat

Native to Europe and North America, inhabiting ecosystems characteristic of the region.

Range

Distributed across Denmark, Norway, Portugal, Sweden, and United States. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

American Bald Eagle

The national bird of the United States and a symbol of American conservation success, bald eagles have a wingspan of up to 2.4 meters and inhabit forests and wetlands near open water across North America. Powerful aerial predators and scavengers, they specialize in fish but also take waterfowl and carrion. Nearly extinct by the 1960s due to DDT poisoning and hunting, the bald eagle recovered dramatically following pesticide bans and the Endangered Species Act.

Concentric Boulder Lichen

<em>Porpidia crustulata</em>, commonly known as the Concentric Boulder Lichen, is a crustose lichen in the family Porpidiaceae formed through a symbiotic relationship between a fungal partner (mycobiont) and photosynthetic green algae (photobiont). Like all crustose lichens, it grows tightly appressed to its substrate—typically siliceous or acidic rock surfaces including boulders, cliff faces, and pebbles in open, well-lit habitats—forming thin, grayish to pale thalli marked by scattered black apothecia (reproductive discs). <em>Porpidia crustulata</em> derives nutrition entirely through photosynthesis conducted by its algal partner, requiring no external organic food source. The species has been documented in Denmark, Norway, Portugal, Sweden, and the United States, suggesting a broad boreal to temperate distribution across the Northern Hemisphere. It is currently classified as Vulnerable by the IUCN, indicating significant conservation concern, likely linked to threats including air pollution, acidification, quarrying of rocky habitats, and changes in land use that reduce the availability of suitable substrates. Crustose lichens are typically slow-growing, long-lived organisms with limited capacity for rapid range shifts in response to environmental change. Biological traits such as individual lifespan, growth rates, and reproductive output remain poorly documented at the population level.