Wrens are small, active songbirds that can be found across North America. They build domed nests out of twigs, grasses, moss, and feathers in sheltered spots like shrubs, trees, or human-made structures. Wrens lay between 4-8 eggs at a time and will have multiple broods over the course of a breeding season. Both male and female wrens participate in feeding and caring for their young. But just how often do parent wrens deliver food to their chicks? The feeding frequency depends on a few key factors.
Number and Age of Nestlings
The number and age of nestlings plays a significant role in how often parent wrens make feeding trips. More babies naturally require more regular feedings. Here’s an overview:
Newly Hatched Chicks
For the first few days after hatching, wren chicks are helpless, blind, and completely dependent on their parents for food and warmth. They need very frequent feedings to fuel their rapid growth and development. Parent wrens will deliver tiny insects and other foods to new hatchlings as often as every 2-5 minutes during peak feeding times. This equates to 12-30 feedings per hour.
Growing Nestlings
As baby wrens grow over the next 7-12 days, their appetite and food demands increase tremendously. Both parents continue to deliver a steady stream of caterpillars, spiders, and other small invertebrates, but the feeding frequency decreases slightly. On average, one parent will return to the nest with food every 3-10 minutes during peak activity, or 6-20 feedings per hour.
Near Fledging
In the final days before leaving the nest, nestling wrens are nearing adult size but still require considerable energy and nutrition. At this stage, parent wrens may visit the nest with food as frequently as every 1-5 minutes during busy times. This works out to 12-60 feedings per hour. The increased food delivery helps ensure the babies are strong and developed enough for fledging.
Time of Day
Parent wrens adjust their feeding schedules based on the time of day and the babies’ needs:
Early Morning
Wren parents start making food deliveries to the nest at first light, around dawn. The early morning hours are a peak feeding time to satisfy the babies’ hunger after a long night. Both parents make frequent trips, visiting every 1-10 minutes (6-60 feeds per hour).
Mid-Day
Feeding activity slows down a bit during the middle of the day when temperatures climb. Adults may visit the nest every 5-20 minutes (3-12 feeds per hour), with a focus on keeping the nestlings cool and shaded.
Late Afternoon
As temperatures cool down in late afternoon, wren parents pick up the pace of food delivery again. They continue making trips every 3-10 minutes (6-20 feeds per hour) to pack in extra nutrition before dark.
Overnight
Feeding essentially halts overnight while the nestlings and parents sleep. The parents may occasionally deliver a late night snack, but generally do not feed again until the early morning.
Other Factors
Beyond the nestling stage and time of day, a few other variables can influence how frequently wren parents visit the nest with food:
Brood Size
Wrens usually raise between 4-8 chicks per brood. More chicks generally equates to higher feeding rates. Small broods of just 2-3 nestlings may be fed a little less often than larger broods.
Food Availability
When insects and other prey are scarce, parent wrens may struggle to find food and be forced to decrease feeding frequency. Abundant food resources allow them to maintain higher feeding rates.
Weather Conditions
Bad weather like heavy rain, high winds, or extreme cold can inhibit the parents’ ability to forage efficiently. This may temporarily decrease feeding frequency until conditions improve. Mild, calm weather is ideal for uninterrupted feedings.
Predation Threats
High predation pressure requires wren parents to be cautious when visiting the nest. They may only make brief feeding stops or avoid the nest temporarily until the threat passes. This can decrease feeding rates. Lower threats allow more continuous care.
Parenting Experience
Older, more experienced wrens that have raised multiple broods become very efficient providers. Their feeding rates may be higher than younger first-time parents.
Feeding Schedule by Nestling Stage
Here is a summary of the typical feeding frequency for parent wrens based on the nestling age and time of day:
Nestling Age | Early Morning | Mid-Day | Late Afternoon | Overnight |
---|---|---|---|---|
Newly Hatched | 12-30 feeds per hour | 12-30 feeds per hour | 12-30 feeds per hour | 0-2 feeds per hour |
Growing (days 3-10) | 6-20 feeds per hour | 3-12 feeds per hour | 6-20 feeds per hour | 0-2 feeds per hour |
Near Fledging | 12-60 feeds per hour | 6-20 feeds per hour | 12-60 feeds per hour | 0-2 feeds per hour |
Feeding Strategies
Wrens use some clever strategies and adaptations to maintain the high feeding rates needed by their young:
– Both parents feed the nestlings, sharing the workload. This allows each parent to spend time away from the nest foraging.
– Wrens build multiple entrance holes to their nests, facilitating rapid entry and exit when delivering food.
– They carry only small food items like individual insects to deliver meals more quickly.
– The birds memorize the locations of the best foraging sites near the nest to reduce travel time.
– Adults will continue feeding nestlings even after leaving the nest, helping the young to transition to independence.
Growth Supported by Frequent Feedings
The exceptionally high feeding rate of wrens is essential to support the nestlings’ extremely rapid growth and development. Here’s some perspective:
– Wren hatchlings start out weighing just 1-2 grams but can reach 16-21 grams by fledging. This is a 700-2000% weight gain in just 10-18 days.
– To achieve this growth, wren nestlings need to consume 25-30% of their body weight in food daily.
– By constantly delivering small meals, the parents ensure the nestlings crop (storage pouch) is rarely empty.
– With a steady stream of caterpillars, spiders, and other protein and fat-rich foods, the babies build muscle, tissue, feathers, and other structures.
– Frequent feedings also allow nestlings to avoid spending energy on thermoregulation, letting them channel nutrition into growth.
Monitoring Feeding Rates
Researchers can get precise data on wren feeding frequency by doing nest watches:
– This involves quietly observing a nest for set time periods and recording each parental visit and food delivery.
– Feeding rates are measured in multiple intervals throughout the day and across various nestling stages.
– The chick’s crop is checked during nest checks before and after feeds to estimate meal size.
– Tracking bands help identify individual parents and determine if both are contributing equally.
– Video cameras at the nest also provide valuable feeding data day and night.
Conclusion
Wren parents are some of the hardest working birds when it comes to delivering food to their chicks. They make hundreds of trips per day, responding to the nestlings’ needs and the circumstances. Newly hatched chicks require feeding every few minutes, while older nestlings need meals every 5-10 minutes at peak times. Regular measurements reveal just how industrious wrens are in their quest to raise each brood successfully. The parents’ tireless efforts underscore how metabolically expensive it is for songbirds to sustain their high reproductive rates. But with persistence and pair cooperation, most wrens are able to keep their chicks well-fed and thriving.