Marsh antwren facts for kids
Quick facts for kids Marsh antwren |
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_-Sao_Paulo,_Brazil.jpg) |
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| Male of subspecies S. a. paludicola | |
| Conservation status | |
| Scientific classification | |
| Genus: |
Formicivora
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| Species: |
acutirostris
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| Synonyms | |
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Stymphalornis acutirostris |
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The marsh antwren (Formicivora acutirostris) is a small bird that mostly eats insects. It belongs to a group of birds called "typical antbirds." This bird lives only in southeastern Brazil.
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Understanding the Marsh Antwren's Name
Scientists often give animals long, scientific names. The marsh antwren's scientific name is Formicivora acutirostris.
There are two main types, or subspecies, of marsh antwrens. These are F. a. acutirostris and F. a. paludicola. Scientists sometimes debate how these birds should be named, but most agree they are both types of marsh antwrens.
What Does the Marsh Antwren Look Like?
The marsh antwren is a small bird, about 13 to 15 centimeters (5 to 6 inches) long. It weighs between 8 and 12 grams (about 0.3 to 0.4 ounces).
Males of the acutirostris Subspecies
Male acutirostris antwrens have a lead gray face with a light stripe above their eye. They also have a whitish crescent shape below their eye. Their head and back are dark chestnut-olive.
Their wings are dark, with bright white tips on some feathers. Their tail is black, sometimes with white tips. Their throat, chest, and belly are lead gray.
Females of the acutirostris Subspecies
Female acutirostris antwrens also have a light stripe above their eye and a whitish crescent below it. But their face has black and white stripes. Their head is olive-brown, and their back is brown to grayish brown.
Their wings look like the males'. Their tail is all black. Their throat and belly are white with heavy black streaks on their chest.
Males of the paludicola Subspecies
Male paludicola antwrens have a white stripe above their eye on a black face. Their head is gray, and their back is dark grayish brown.
Their wings are very dark brown with white edges. Their tail is black with white tips on the two outer feathers. Their throat, belly, and thighs are black.
Females of the paludicola Subspecies
Female paludicola antwrens have a white stripe above their eye on a gray face. Their head is gray, and their back is dark grayish brown.
Their wings are similar to the males'. Their throat and belly are white with black spots. Their thighs are black with white tips.
Where Does the Marsh Antwren Live?
The marsh antwren lives in different parts of southeastern Brazil. The acutirostris subspecies is mostly found along the coast in Paraná and northern Santa Catarina. It also lives a bit further south in Rio Grande do Sul.
The paludicola subspecies lives further north in São Paulo state, near the city of São Paulo. It is found in fewer than 20 locations.
Marsh Antwren Habitat
As its name suggests, the marsh antwren mostly lives in marshes near coasts and rivers. It also lives in flooded plains and areas where mangroves meet drier land. These places often have changing water levels.
The bird prefers thick plants that are less than 1 meter (3 feet) tall. The acutirostris subspecies lives from sea level up to about 25 meters (82 feet) high. The paludicola subspecies lives at higher elevations, between 600 and 760 meters (1,969 and 2,493 feet).
Marsh Antwren Behavior
Movement
Marsh antwrens usually stay in the same area all year round. However, they might move short distances between nearby places.
Feeding Habits
The marsh antwren's diet is mostly made up of arthropods, which are creatures like insects and spiders. It looks for food alone, in pairs, or in family groups. They stay hidden in the thick marsh plants.
They find food by picking insects off grass, reeds, and leaves. They often reach or lunge to grab their prey. Sometimes they make short jumps or quick flights from a branch to get insects from the underside of leaves.
Reproduction
The acutirostris subspecies breeds from August to February. The breeding time for F. a. paludicola is not fully known, but it seems to be mainly from October to February.
The nest of the acutirostris antwren is shaped like a cup. It is made from plant fibers and spider silk. Sometimes, leaf pieces are woven into the nest, and it's lined with soft fibers. Nests are often hung in tall grass or reeds, usually within 2 meters (7 feet) of the ground.
Both the male and female birds take turns sitting on the eggs. They lay two white eggs with irregular brown spots. Each egg is about 19 by 14 millimeters (0.75 by 0.55 inches) and weighs about 1.8 grams (0.06 ounces). We don't know how long it takes for the eggs to hatch or for the young birds to leave the nest.
Vocalization
The song of the acutirostris subspecies sounds like quick, double notes. The first note is usually stronger and lower. These notes repeat in a slightly uneven rhythm.
The paludicola subspecies sings a fast, steady sequence of double notes. The first note goes down slightly, and the second note has a small up-and-down sound. Both subspecies also have a variety of calls that are similar to each other.
Status of the Marsh Antwren
The marsh antwren faces serious threats. Scientists consider the acutirostris subspecies to be "Near Threatened." This means it could become endangered soon. Its population, estimated between 5,000 and 10,000 adult birds, is shrinking.
The biggest threat to this bird is invasive plants, which are plants that grow too much and take over its habitat. Some areas where it lives are also being destroyed by fires, new buildings, and landfills. Pollution and climate change are also problems.
The paludicola subspecies is in even greater danger. It is listed as "Critically Endangered." This means it is at a very high risk of becoming extinct. There are fewer than 700 adult birds left. The marshlands around São Paulo, where this bird lives, have almost completely disappeared over the last 100 years.
