Wrens are small, energetic songbirds that belong to the family Troglodytidae. They are known for their loud, complex songs and active foraging habits. Wrens build dome-shaped nests out of twigs, grasses, moss, and other materials, often in hidden locations like tree cavities or dense shrubbery.
Female wrens lay clutches of 4-8 tiny eggs and incubate them for around 14 days until they hatch. But do wrens actually sit on their eggs like chickens or other birds? Or do they use alternative incubation strategies? Let’s take a closer look at wren nesting habits and how wren eggs are incubated and hatched.
Wren Nesting Habits
Wrens are solitary, not colonial, nesters. A mated pair will build a nest together at the start of breeding season, using materials like twigs, grass, feathers, moss, spider egg sacs, paper, and more depending on the species. The nests are usually domed with a side entrance hole and lined with softer lining materials. Nests can be built in trees, shrubs, vine tangles, rock crevices, old woodpecker holes, nest boxes, buildings, and other sheltered spots.
Different wren species show preferences for certain nesting locations. For example:
- Carolina wrens often nest in shrubs or sheltered spots on porches and buildings.
- Bewick’s wrens nest in cavities like old woodpecker holes.
- Cactus wrens build nests in cacti or thorny desert bushes.
- Marsh wrens weave nests out of reeds and grasses over the water.
Once the nest is built, the female wren lays a clutch of 4-8 small white eggs. She will lay one egg per day until the clutch is complete.
Do Wrens Sit on Their Eggs?
Yes, once the full clutch of eggs has been laid, the female wren settles down to incubate them. Incubation is the process of sitting on the eggs to provide warmth for embryonic development.
The body heat provided by a brooding parent bird like the wren hen is crucial for incubating the eggs and developing the chicks inside. Like other small songbirds, wrens have body temperatures around 105°F (40°C). This transfers through the bird’s brood patch – a bare patch of skin on the belly – directly to the eggs.
Female wrens develop their brood patch as they lay eggs. More blood vessels grow into the region to help transfer body heat. The brood patch is rich in blood vessels and very efficient at warming the eggs.
Once incubation starts, the female wren will remain on the nest for long periods, only leaving briefly to find food and water. She may take short breaks but returns quickly so the eggs don’t cool down too much. Cooling can slow embryonic development or even kill the chick.
Both parents may incubate the eggs, but usually this duty falls mainly to the female. She patiently sits through heat, cold, wind, rain, and anything else to keep her eggs warm. Incubation lasts for 12-17 days depending on species until the eggs hatch.
How Do Wren Chicks Hatch?
About two weeks into the incubation period, the baby wrens are ready to hatch out. They break free using an egg tooth – a sharp bump on their beak. This allows them to chip away at the egg from inside until they make a hole, a process called pipping.
Once pipped, the wren chicks can take 12-36 hours to fully emerge. They eventually squeeze through the hole, damp and exhausted. The female continues to brood them until they dry off and get stronger, providing essential warmth and protection.
Newly hatched wrens are altricial – helpless, blind, and naked. Their eyes remain closed for 5-11 days. But they grow incredibly fast thanks to devoted feeding by both parents who forage tirelessly to satisfy their hungry young.
Within two weeks, the chicks are too big and active to all fit inside the nest. They overflow out of the entrance as both parents continue to feed and care for them. At 15-21 days old, the young wrens will leave the nest for good but stay close by as their parents still bring them food.
Key Facts on Wren Incubation and Hatching
- Female wrens develop a brood patch to transfer body heat to eggs.
- Females incubate the eggs alone for 12-17 days depending on species.
- Incubating wrens rarely leave the nest to maintain proper temperature.
- Baby wrens pip internally and break free using an egg tooth.
- Hatchlings are altricial – naked, blind, and helpless at first.
- Parents work together to feed and care for the chicks after hatching.
Conclusion
Incubation is a key part of the wren nesting process. Female wrens dutifully sit on their clutch of 4-8 eggs for up to 17 days. Their constant body heat transfers through the brood patch to develop the chicks inside. Once hatched, the parents continue to provide food and protection as the altricial nestlings grow. Within a few weeks, the young wrens fledge the nest. So in answer to the original question – yes, wrens do firmly sit on their eggs just like chickens and other birds to successfully incubate and hatch their chicks!