Horned Grebe and Slavonian Grebe are two species of grebe birds that belong to the Podicipedidae family. They are closely related species and can sometimes be confused with each other. However, there are some key differences between the two species.
Appearance
Horned Grebes and Slavonian Grebes have similar body shapes and color patterns. They are small waterbirds with short necks, small heads, and slender bills. Both species have black heads, white underparts, and gray backs in breeding plumage. However, there are some differences in their appearance:
- Horned Grebes have bright rusty-red neck feathers that extend like “horns” behind their eyes in breeding plumage. Slavonian Grebes lack these distinctive horn-like neck feathers.
- Slavonian Grebes have brighter red eyes than Horned Grebes, whose eyes are yellow.
- Slavonian Grebes have a steeper forehead and stubbier bill than Horned Grebes.
- In non-breeding plumage, Horned Grebes have white cheeks while Slavonian Grebes have dark gray cheeks.
Size
Horned Grebes are slightly larger than Slavonian Grebes. Key size differences:
- Horned Grebe length: 13.4-16.1 in (34-41 cm)
- Slavonian Grebe length: 12.2-14.2 in (31-36 cm)
- Horned Grebe wingspan: 22.8-26.8 in (58-68 cm)
- Slavonian Grebe wingspan: 20.9-23.6 in (53–60 cm)
Range and Habitat
Horned Grebes and Slavonian Grebes have overlapping but distinct natural ranges and habitat preferences:
- Horned Grebes breed across northern North America and Eurasia, migrating south to winter along the Pacific, Gulf, and Atlantic coasts. They occur on inland lakes and marshes.
- Slavonian Grebes breed in central Eurasia, migrating to the Mediterranean, Black Sea, Caspian Sea, and parts of China for winter. They primarily live on alkaline and saline lakes.
- There is overlap between the species in parts of western North America and interior Asia where both grebes may occur during migration or winter.
Behavior
Both Horned Grebe and Slavonian Grebe behaviors are adapted for swimming and diving after small fish and invertebrates:
- They propel themselves with their feet while swimming on the water surface.
- They can dive and swim underwater using their feet for propulsion.
- They build floating nests among emergent vegetation.
However, there are some behavioral differences:
- Horned Grebes are more likely to winter in coastal marine habitats than Slavonian Grebes.
- Slavonian Grebes engage in elaborate courtship displays like “rushing” across the water surface and “weed dancing.” Horned Grebe displays are less elaborate.
- Horned Grebes are more territorial than Slavonian Grebes during breeding season.
Diet
As aquatic insectivores, Horned Grebes and Slavonian Grebes feed mainly on small fish, crustaceans, and aquatic invertebrates. Their diets are very similar and include:
- Small fish like smelt, sticklebacks, and minnows
- Shrimp, crayfish, and other crustaceans
- Aquatic insects
- Tadpoles and small frogs
Both species forage while swimming, floating, and diving beneath the water’s surface. They may also occasionally eat plant material.
Conservation Status
Horned Grebe and Slavonian Grebe have different conservation statuses and population trends:
- Horned Grebe is classified as Least Concern by the IUCN Red List due to its large range and population.
- Slavonian Grebe is classified as Near Threatened by the IUCN Red List with an estimated global population between 22,000-44,000. Populations are declining in parts of its range.
Threats to both species include habitat loss, pollution, disturbance, and fishing bycatch. Slavonian Grebes are more vulnerable overall likely due to their smaller population size and more restricted range.
Taxonomy
Horned Grebe and Slavonian Grebe are classified in the Podicipedidae family along with other grebes. There has been some debate about their taxonomy:
- Traditionally placed in the genus Podiceps
- Some authorities place them in the genus Tachybaptus
- Considered part of a superspecies along with the Alchon Grebe
- Recent genetic evidence suggests they may not be as closely related as previously thought
They are currently classified as:
- Podiceps auritus – Horned Grebe
- Podiceps auritus – Slavonian Grebe
Key Differences Summary
In summary, while Horned Grebe and Slavonian Grebe are similar species, some key differences are:
Trait | Horned Grebe | Slavonian Grebe |
---|---|---|
Neck Feathers | Rusty-red “horns” | No “horns” |
Eye Color | Yellow | Red |
Size | 13.4-16.1 in long | 12.2-14.2 in long |
Range | Northern North America, Eurasia | Central Eurasia |
Habitat | Inland lakes and marshes | Alkaline, saline lakes |
Conservation Status | Least Concern | Near Threatened |
Conclusion
In conclusion, while Horned Grebe and Slavonian Grebe share similar body plans and behaviors as members of the grebe family, they differ significantly in appearance, size, geographic range, habitat preferences, and conservation status. They are considered separate species. Horned Grebe tends to be larger, has distinctive feathering, and is more widespread and abundant than the rarer and more range-restricted Slavonian Grebe. Proper identification requires paying attention to field marks like the horned feathers, eye color, bill shape, and plumage details. Understanding the differences between these two species is important for birders interested in properly identifying them.