Marsh Wren

The Marsh Wren is a small songbird that is often identified by their song, not their appearance. The males are capable of learning up to 200 unique song types during their early days. During their adult life, males use this singing ability to defend their territory.

About Marsh Wrens

These birds are native to the North American region and can only be found in Mexico, Canada, and the United States. The birds native to the southern region usually do not migrate at any point of the year. However, northern birds migrate to southern regions (such as Florida) in the winter.

They are secretive and skittish birds. It is tricky to spot them as they tend to only fly in short rapid bursts and swing from cattail and bulrush strands to move undercover in the marshlands while hunting for food or nesting territory. Their black crowns and rusty-brown bodies provide perfect camouflage in the marshland.

The males can produce different songs to suit different purposes. While nesting, the males produce bubbly melodious songs when the female is near. When predators are near, the male can produce sharp trills to warn of their presence.

While their ability to learn and reproduce numerous song types is remarkable and unique, there is another critical feature that sets Marsh Wrens apart from most other bird species. Male Marsh Wrens are polygynous. This means that a single male bird will usually mate with more than one female bird at a time. Marsh Wrens seem particularly interesting, don’t they? Let’s learn a little more about them.

● Marsh Wrens Photos, Color Pattern, Song
● Marsh Wrens Size, Eating behavior, Habitat
● Marsh Wrens Range and Migration, Nesting

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Marsh Wren Color Pattern

Marsh Wrens are one of the few birds that undergo two complete molts a year. Adult Marsh Wrens have two molts: one in the fall (basic plumage) and one at the end of winter (alternate plumage). One discrepancy observed is that the male plumage is brighter than the female plumage.

The juvenile plumage consists of monochromatic brown feathers accompanied by a dull black crown. While similar to the adult plumage, the juvenile plumage lacks distinctive white streaks on the back and has fewer black markings on the body.

Marsh Wrens acquire the Basic I plumage 40 to 100 days after the hatching, through a partial molt. The birds have cinnamon-brown underparts that are faintly barred black in places. A whitish coloring stretches from the neck to the belly, accompanied by a buffy wash on the sides. A black triangular region, striped with white, can be observed on the bird’s back. A distinct white superciliary line forms and the crissum is more clearly barred.

The first nuptial or alternate plumage is obtained by late January. The plumage is similar to the basic plumage except, the undersides are whiter and the baring on the crissum and flanks is less noticeable.

The adult basic plumage is obtained the following August. This is similar to the Basic I plumage but the wings and tails appear greyer and wing-and-tail coverts and tertials are more densely revealed. The adult alternative plumage (similar to the adult basic plumage) is acquired the following spring.

The molting strategy alleviates the feather scuffing generated from moving through marshy lands. The cyclical moltings help maintain the plumage. Interestingly, the molting is independent of sex or geographical variation.

Description and Identification

Marsh Wrens are tiny, plump birds that have distinctive black crowns and streaked brown bodies. However, it is difficult to identify Wrens by their appearance as these bodies are designed to be camouflaged between native plant species in the marshlands. A birdwatcher needs to be patient and wait for the bird to jump to the top of cattail stalks.

Nevertheless, the loud gurgling noises produced by male wrens are unmistakable. The eastern Marsh Wrens, in particular, produce bubbling musical notes that end in a trill. Therefore, one is likely to hear these birds before sighting them.

Wrens are commonly mistaken for Sedge Wrens due to their similar appearance. Even though Marsh Wrens are bigger and more brightly colored than the Sedge Wrens, it is much easier to distinguish the two by their song.

Marsh Wren Song

It is important to note that while Marsh Wrens are primarily known to be songbirds, only males produce the distinctive songs the species is known for. Large geographical variation in song types is observed.

Nestlings use basic sounds to plead for food in the early days. They become increasingly vocal, making gurgling noises a few days after hatching and can be heard up to 30 meters away. It is easiest to hear adult males in the early hours of the morning and sometimes throughout the night. The birds can also be heard singing multiple songs in quick succession during sexual encounters.

While females do not sing, they use vocalizations such as click or chuck calls to locate food like their male counterparts. When returning from foraging in foreign territory, males emit loud calls that make that sound “tscheew, tscheew, tscheew”.

Male birds also use unique calls to warn that predators may be near. When Marsh Wrens are followed by Blackbirds, they produce a rapid series of trills like “turr, turr, turr, turr”. Another fascinating feature is that male Marsh Wrens are capable of imitating new songs presented to them (on tapes) when they are young, even if the songs belong to other species such as Sedge Wrens and Yellow Warblers.

Marsh Wren Size

Marsh Wrens are among the smallest Wren birds. The average adult measures up to 104–140 mm in total length and weighs between 9 to 14 grams.

Substantial sexual dimorphism is observed. Male wingspans are roughly 3 mm longer than female wingspans and males, on average, are 1.2 grams heavier.

Furthermore, Marsh Wren’s size differs geographically. A study finds that eastern Marsh Wrens tend to have heavier brains, bodies, and testes than their western counterparts.

Marsh Wren Behavior

Marsh Wrens are territorial. Males sing to establish their territories and are hostile when defending them. Sometimes a challenger will fly into an established zone and aim to out-sing the current occupant to increase his own territory.

A shocking fact is that both males and females have been observed to destroy nearby nests by using their beaks to peck at eggs and kill young fledglings. This is thought to be a tactic that the birds use to reduce competition for food and other resources.

The birds are generally very active. They take short flights using rapid wing beats and usually leap between the reeds like “feathered gymnasts”. The male uses a fluttering flight to launch far above the territory to scope out any potential dangers.

A unique feature of the male Marsh Wrens is that they are polygynous. A single male will mate with two or more females (the females are monogamous). The proportion of males attracting two or more females varies between populations. The figures range from as low as 5% in Georgia to a whopping 50% in Seattle, Washington. Even though the sex ratio remains 1:1 across states!

Marsh Wrens’ courting ritual is fascinating. The males court the females by launching a rapid valley of songs towards any female that approaches his territory. Researchers have observed that when males escort females, he appears nervous as he bows with his tail held high.

What do Marsh Wrens Eat?

These birds are opportunistic and consume any accessible invertebrate. Most often they consume spiders (15% of all food eaten by volume) and freshwater insects such as bees and beetles.

Wrens usually forage food near the water’s surface. They are constantly on the move, hopping between stalks to catch insects during the warmest times of the day. Curiously, evidence suggests that Marsh Wrens do not create food stores and only eat when prey is readily available.

Marsh Wren Habitat

As the name suggests, Marsh Wrens primarily live in marshlands. The birds inhabit marshlands in Mexico, the United States, and Canada. A common feature is that most males choose to build their nests in cattail strands. When the marsh dries up near the shallower cattail strands, the males quickly switch their nests to bulrush strands due to its deeper penetration.

It is intriguing to note that while most Wrens are acclimatized to still freshwater marshes, the Georgia Marsh Wrens have adapted to saltwater marshes in the state by using the native cordgrass rather than cattails or bulrush. Additionally, resident Florida birds have adapted to salty tidal creeks by using native cordgrass and sawgrass to house their nests.

The birds overwinter in habitats with dense, wet soil and low vegetation cover. The differences between lands inhabited during breeding and non-breeding seasons are negligible.

Range and Migration

Marsh Wrens reside in the North American region and cannot be found anywhere else in the world. The migratory behaviors of native subspecies vary greatly as the decision to migrate seems to hinge on the severity of winter faced.

The winter tends to be the harshest in northern inland regions while southern coastal regions face mild winters. This explains why most native southern species (in California and Mexico for example) appear to migrate the least while northern inland natives (in Alberta and Michigan for example) appear to migrate the most.

Evidence suggests that Florida is the most attractive destination for northern birds. While migrating, the birds tend to fly at low altitudes during the night and aim to arrive in Florida by mid-October.

Another unusual disparity observed is that juveniles on average tend to prefer migrating to coastal regions whereas adults remain relatively further inland during winters.

Marsh Wren Lifecycle

Female Marsh Wrens take up to 6 weeks to complete one breeding cycle. There are two broods per season. The clutch size is usually 3-10 eggs. These eggs are brown with dark spots and hatch in the order that they were laid.

The incubation period is 12-16 days and the nesting period is 13-15 days. Juvenile birds mature relatively fast as they acquire the first basic plumage around 50 days after hatching. In the spring, the bird acquires the alternate plumage which marks the beginning of the breeding season.

Accurate lifespan estimates are unavailable as many researchers found that many birds that migrate do not return to the original marshland. Nonetheless, scattered evidence suggests that 40% adult males and 33% adult females survived from 1 year to the next.

Nesting

Nesting begins when the temperature hits about 15 degrees Celsius, during April and May each year. Although males generally construct the nest by gathering materials such as water-soaked strips of grass and small stems, females line the nests by stealing materials from neighboring nests. When completed, the nests are cup-shaped and have a tunnel-like doorstep. The walls are 2 cm thick and the inner cavity is about 8×13 cm.

An interesting feature is that males build multiple nests, many of which are not used. This probably helps them practice and have backups in case the primary nest is destroyed.

Anatomy of a Marsh Wren

Marsh Wrens are stocky, round-bodied birds. It is small compared to other Wren birds. The bill is relatively long compared to other Wrens. They have long tails that are black with white stripes.

Given their size, they are mistaken for their close relative, the Sedge Wren. Although the two have similar colorings, Marsh Wrens are significantly bigger and have brighter colors. Sedge Wrens also have much smaller bills.

Final Thoughts

Marsh Wrens are clearly one the most innovative birds in the world considering their nest-building and hunting strategies. The level of effort that they put in to protect their family is truly remarkable.

The feature that differentiates them from other birds is that the males are polygynous. It is possible that this behavior has contributed to the continued survival of the species given the harsh competition and cruel tendencies of the species.

They are capable of wreaking havoc in the lives of other Marsh Wrens and related species. While many of their tactics seem cruel, it has allowed them to survive and keep their population thriving.

Ornithology

Bird Watching Academy & Camp Subscription Boxes

At Bird Watching Academy & Camp we help kids, youth, and adults get excited and involved in bird watching. We have several monthly subscription boxes that you can subscribe to. Our monthly subscription boxes help kids, youth, and adults learn about birds, bird watching, and bird conservation.

Bird Watching Binoculars for Identifying Marsh Wrens

The most common types of bird watching binoculars for viewing Marsh Wren are 8×21 binoculars and 10×42 binoculars. Bird Watching Academy & Camp sells really nice 8×21 binoculars and 10×42 binoculars. You can view and purchase them here.

Marsh Wren Stickers

Stickers are a great way for you to display your love for bird watching and the Marsh Wren. We sell a monthly subscription sticker pack. The sticker packs have 12 bird stickers. These sticker packs will help your kids learn new birds every month.

Bird Feeders For Marsh Wrens

There are many types of bird feeders. Here are our favorite bird feeders for your backyard. We use all of these bird feeders currently. Kids will have a great time watching birds eat at these bird feeders. Using this collection of bird feeders will provide a wide variety and many types of birds.

Best Bird Houses For Marsh Wrens

There are many types of bird houses. Building a bird house is always fun but can be frustrating. Getting a bird house for kids to watch birds grow is always fun. If you spend a little extra money on bird houses, it will be well worth every penny and they’ll look great.