Purple martins are migratory swallows that breed across North America. They are the largest swallow species in North America, known for their speed and agility in flight. Purple martins eat only insects, catching them in midair or plucking them from leaves and branches. Baby purple martins rely completely on their parents to provide them with food in the form of insects for the first few weeks after hatching.
What do adult purple martins eat?
Adult purple martins are aerial insectivores, meaning they catch and eat insects while in flight. A purple martin’s diet consists entirely of insects and other arthropods such as:
- Dragonflies
- Damselflies
- Flies
- Bees
- Wasps
- Butterflies
- Moths
- Mayflies
- Grasshoppers
- Crickets
- Cicadas
Purple martins feed by flying with their beaks open to snatch up insects mid-flight. They also forage by perching on branches and plucking insects off leaves. An individual purple martin can consume thousands of insects each day. Their aerial hunting skills make purple martins highly effective at controlling mosquito and other flying insect populations.
When do purple martins nest and raise young?
Purple martins migrate thousands of miles from their wintering grounds in South America to nesting sites across North America each spring. They arrive at their breeding grounds from late March through May depending on the region. Males arrive first to scout out nesting locations, followed shortly after by females.
Purple martins nest in colonies, with several pairs nesting in close proximity to each other, often using manmade nest boxes or gourds. Females lay 4-6 eggs which incubate for about 15 days before hatching. Once hatched, both parents share responsibility for feeding the nestlings.
For the first week after hatching, the chicks are blind, naked, and completely dependent on their parents for food and warmth. At this stage the parents take turns bringing food back to the nest almost continuously from dawn to dusk.
What do baby purple martins eat?
For the first week to ten days after hatching, baby purple martins eat the same insects captured in flight that adult martins eat. The parents catch insects in their beaks then return to the nest to feed the insects to the chicks by regurgitating the insects for the babies to eat.
Typically, the diet consists of:
- Flies
- Moths
- Bees
- Wasps
- Dragonflies
- Butterflies
- Grasshoppers
- Crickets
The parents try to provide a variety of insects to ensure the nestlings get adequate nutrition for growth. As the chicks get older, the parents may bring back larger insects for them to eat. Caterpillars are also an important food source once the chicks are 10-12 days old and able to digest them.
How do the parents feed the nestlings?
To feed their young, adult purple martins capture insects in their beaks while flying, store them in their throats, then return to the nest. There, the parents regurgitate the insects into the open mouths of the begging chicks. Parent purple martins can make hundreds of feeding trips each day to provide enough food for their rapidly growing brood.
Young purple martins beg for food by stretching their necks high and opening their mouths wide. This signals to the parents that they are hungry. The parents respond by feeding each chick multiple insects at a time, often until its crop (the storage pouch in the throat) is full. Nestlings may consume up to half their body weight in insects daily.
How often do the parents feed the nestlings?
For the first week after the eggs hatch, the parents make near constant feeding trips to the nest, from dawn to dusk, to satisfy the appetites of the tiny nestlings. The feeding frequency depends on a few factors:
- Number of chicks – more chicks mean more mouths to feed
- Size of chicks – as chicks grow, they require more food
- Time of day – feedings increase around dawn and dusk
- Weather – cool or rainy weather may depress insect activity requiring more foraging
Typically, in good weather, parent purple martins make 35-40 feeding trips per hour to the nest in the first week after hatching. This equates to about 500 trips per day by each parent. The rate declines slightly as the chicks get older.
How do the feeding habits change as the chicks grow?
In the first week after hatching, the nestlings are fed pre-digested insects regurgitated by the parents. By 10-12 days old, the chicks are able to digest whole insects. The parents gradually provide more whole insects as the chicks’ digestive systems mature.
Around 2-3 weeks old, the chicks are able to handle larger prey like dragonflies, moths, and butterflies. The parents may even bring back small vertebrates like tree frogs or lizards on occasion. Nestlings over 18 days old may get practice flying by hovering at the nest entrance while being fed.
By the third week, the chicks beg and jostle vigorously for position during feedings. The parents taper off feedings as the chicks get close to fledging at 4 weeks old. Just before fledging, the parents typically stop bringing food to the nest, forcing the young martins to leave the nest in search of food.
What happens if the parents can’t find enough food?
Purple martins are dependent on catching flying insects to feed themselves and their young. Cold, rainy, or windy weather can make flying and hunting insects difficult. Similarly, pesticide use can reduce insect populations in an area.
If inclement weather or lack of insects makes finding food difficult, nestlings may not get adequate nutrition. Growth and development of chicks will be slowed. Parents may even abandon a nest if they cannot sustain the chicks. Providing supplemental feeders with mealworms or crickets near purple martin colonies can help the parents in times of low food availability.
Conclusion
Baby purple martins rely completely on their parents to supply them with insects for the first few weeks after hatching. The parents work tirelessly to capture enough flies, bees, moths, butterflies and other insects to satisfy the chicks’ voracious appetites. Regurgitation is key, as the parents must pre-digest the insects to make them palatable for newly hatched chicks. Feeding frequency decreases as the nestlings grow and their digestive systems mature. Understanding the unique feeding behaviors of these aerial insectivores provides insight into their reproductive strategies and the bonds between purple martin parents and offspring.