Larks are a family of small to medium-sized passerine birds that are found throughout Europe, Asia, Africa, and North America. There are over 90 different species of larks, making them one of the most widespread groups of birds in the world. Larks occupy a diverse range of habitats, from grasslands and agricultural fields to deserts and alpine regions. Understanding where different lark species originate from provides insights into their evolutionary history and ecology.
Native Range of Larks
The ancestral home of larks is considered to be the arid grasslands and deserts of Africa, the Middle East, and Central Asia. This region harbors the highest diversity of lark species, with over 60 species present. Many of these species have relatively restricted ranges confined to North Africa, the Sahel region, the Arabian Peninsula, and west-central Asia. Examples include the Bar-tailed Lark, Dunn’s Lark, Hoopoe Lark, and Temminck’s Lark, which are found nowhere else except their native desert habitats.
From their ancestral homeland, larks expanded their range into Europe, South Asia, and North America. Europe is home to 19 species of larks, including the ubiquitous Skylark, known for its melodious song. Eleven lark species are native to South Asia, ranging from the Bengal Bush Lark of India to the Mongolian Lark inhabiting the high Tibetan Plateau. Five species occur naturally in North America, such as the widespread Horned Lark and the island-dwelling Skylark of Cuba.
Habitat Preferences
Different groups of larks occupy distinct habitats that match their evolutionary adaptations:
- Desert and grassland species: Depend on open habitats with sparse vegetation, including desert larks of North Africa and southwest Asia and grassland larks of Central Asia.
- Agricultural larks: Thrive in human-altered environments like farmlands and pastures. Example species include Eurasian Skylark, Crested Lark, and Greater Short-toed Lark.
- Alpine larks: Adapted to cold, high-altitude environments in mountains. Examples are the Horned Lark and Shore Lark.
- Bush larks: Inhabit forests, thickets, and scrublands. Mostly found in Africa, southern Asia, and Indonesia.
The native distribution of larks mirrors the availability of their preferred habitats. Open-country specialists like the Hoopoe Lark are restricted to arid grasslands, while bush larks occupy tropical forests and scrublands. Agricultural development has enabled species like the Skylark to expand beyond their ancestral range. Alpine larks are limited to suitable mountainous areas.
Evolutionary History
Larks are an ancient lineage dating back to the Oligocene epoch over 30 million years ago. The early diversification of larks was likely driven by the spread of open grassy biomes. Molecular studies reveal that most extant genera of larks originated during the Miocene as grasslands expanded, providing new ecological opportunities.
Several phylogenetic groups of larks can be identified:
- True larks: The largest radiation encompassing over 70 species. Primarily from Africa, Europe, and Asia.
- Bush larks: Around 20 species adapted to scrubby habitats of Africa and Asia.
- Horned larks: Holarctic species adapted to tundra and alpine zones.
- Woodlarks: Small clade of forest-dwelling species.
These major groupings reflect separate colonization events of new habitat types and geographical regions by ancestral larks. Hybrid zones occur where closely related lark species come into contact, such as between Horned Larks and Shore Larks in Siberia. Overall, larks exhibit a pattern of repeated ecological specialization across diverse environments over their long evolutionary history.
Geographic Variation
Many lark species show extensive subspecific geographic variation, with multiple recognized subspecies occupying discrete ranges. Well-studied examples include:
- Horned Lark: Twenty recognized subspecies across North America, varying in plumage color and size.
- Crested Lark: Nine subspecies differing in vocalizations and color in Africa, Europe, and Asia.
- Skylark: Five main subspecies groups in Europe and northern Asia with range boundaries at major mountains and rivers.
This geographic variation reflects local adaptation and isolation in different environmental regions. Physical barriers like mountains and rivers promote divergence between subspecies as gene flow is restricted. Ongoing study is focused on understanding patterns of subspecies formation and hybridization in larks.
Key Native Regions
The major native regions occupied by diverse lark lineages include:
Region | Notable Lark Species |
North Africa | Thick-billed Lark, Bar-tailed Lark, Dunn’s Lark |
Sahel Zone | Chestnut-backed Sparrow-lark, Black-crowned Sparrow-lark |
Southwest Asia | Hume’s Lark,Large-billed Lark, Bimaculated Lark |
Central Asia | Mongolian Lark, Eurasian Skylark, Oriental Skylark |
Europe | Woodlark, Crested Lark, White-winged Lark |
South Asia | Malabar Lark, Sykes’s Lark, Oriental Skylark |
North America | Horned Lark, Skylark, Shore Lark |
These centres of lark diversity reflect the ancestral origins and adaptive radiation of larks across their global range. The highest richness occurs in the arid grassland belt stretching from North Africa through southwest and central Asia, the evolutionary cradle of many lark groups.
Conclusion
Larks exhibit a distinct biogeographic pattern, originating in Africa and diversifying into specialized lineages associated with deserts, grasslands, agricultural fields, mountains, and other open habitats. Their current native distributions reflect this evolutionary expansion over tens of millions of years, as well as ongoing local adaptation. Several geographical centres of lark diversity stand out, including North Africa, southwest Asia, Central Asia, and South Asia. Understanding the native ranges of larks provides insights into their ecology and evolutionary relationships.