Bobolinks are a type of small blackbird found in grasslands across North America. The diet of baby Bobolinks consists primarily of insects that are rich in protein to support their rapid growth and development. In this article, we’ll take a look at what baby Bobolinks eat and how their diet changes as they mature.
Diet During the Nestling Stage
For the first week after hatching, Bobolink chicks are completely dependent on their parents for food. The female Bobolink does most of the feeding during this time, regurgitating insects directly into the gaping mouths of the chicks. The male will occasionally help with feeding, but his role is minor compared to the female.
During the nestling stage, the diet of baby Bobolinks consists almost entirely of insects and other small invertebrates. Some of the most common foods include:
- Grasshoppers
- Crickets
- Beetles
- Caterpillars
- Spiders
- Ants
- Flies
- Aphids
- Moths
The parents will scout the area around the nest to find abundant sources of insects to feed the demanding chicks. Soft-bodied caterpillars are a favorite as they can be easily regurgitated and provide lots of protein. As the chicks get older, the parents may bring back larger insects and even feed them whole.
Diet During the Fledgling Stage
After a week in the nest, Bobolink chicks are ready to fledge and leave the nest. At this stage, the chicks are covered in juvenile feathers and are able to hop around on the ground. However, they are still unable to fly effectively or gather their own food. The parents continue to care for the fledglings, feeding them for 2-3 weeks after they leave the nest.
During the fledgling stage, the diet is still focused on protein-rich insects but includes a wider variety. Some new additions may include:
- Dragonflies
- Damselflies
- Butterflies and moths
- Snails and slugs
- Spiders and other arthropods
The parents lead the fledglings around the fields and grasslands, helping them learn to find insects on their own. But the young birds still rely almost completely on the parents to actually catch and deliver food to them.
Transition to Self-Feeding
By about 18-21 days after leaving the nest, young Bobolinks are ready to feed themselves and no longer depend on their parents. Their flying skills have improved enough to start catching insects on their own. Their diet remains focused on protein-rich invertebrates, but they are able to capture a wider range of prey.
Some of the insects and other arthropods that juvenile Bobolinks will target include:
- Grasshoppers
- Crickets
- Leafhoppers
- Aphids
- Caterpillars
- Beetles
- Ants
- Bees
- Wasps
- Flies
- Spiders
- Mites
They use their conical beaks to pluck insects from leaves and stems while perched, or snatch them from the air during short flights. By the end of summer, juvenile Bobolinks are adept insect hunters.
Transition to a Seed-Based Diet
By the time late summer and early fall arrive, Bobolinks undergo a dietary shift and begin eating more seeds. This coincides with the formation of large seed heads on grasses and other plants. While insects are still part of their diet, seeds become a primary food source as the birds prepare for migration.
Some of the small seeds commonly eaten by Bobolinks in late summer and fall include:
- Grass seeds
- Sedge and rush seeds
- Millet
- Canary grass
- Ragweed
- Smartweed
- Various cereal crops
Bobolinks use their conical beak to efficiently crack open and hull these tiny seeds. This diet rich in carbohydrates provides the energy needed to fuel the long migratory journey south for the winter.
Diet on the Wintering Grounds
From September to March, most Bobolinks live in grasslands and agricultural areas in southern South America. Here, rice fields provide an abundant source of food.
The diet during the winter consists primarily of:
- Rice
- Various small grass and weed seeds
- Insects like termites, beetles, and grasshoppers
Large flocks of Bobolinks forage together in rice paddies and grasslands. Their ability to eat seeds helps them thrive in these habitats through the winter.
Changes in Diet from Hatchling to Adult
The diet of Bobolinks undergoes significant changes from the time they hatch until they reach adulthood:
Stage | Diet |
---|---|
Nestling | Regurgitated insects provided by parents, especially caterpillars |
Fledgling | Insects captured by parents, gradually increasing in size and variety |
Juvenile | Self-caught insects and arthropods |
Late Summer/Fall | Transition to seeds from grasses, sedges, and crops |
Winter | Seeds of rice, grasses, and weeds; some insects |
Adult | Greater proportion of seeds than insects in the diet |
As they grow and develop, Bobolinks gradually shift from being fed soft insects by their parents to being independent hunters catching a wide range of prey. By adulthood, seeds become the primary component of their diet, supplemented by insects.
Unique Adaptations for Feeding
Bobolinks have some physical adaptations that help them catch insect prey and feed on seeds:
- Conical beak – The long, pointed beak is perfect for plucking seeds and insects.
- Brushed tongue – The tip of the tongue has hair-like bristles that help sweep up seeds and handle insects.
- Large eyes – Their eyes are positioned on the sides of the head, giving them a wide field of view to spot prey.
- Short legs and rounded wings – Allow for maneuverability during low, bounding flights through vegetation to grab insects.
Importance of Insects in the Diet
Although they switch to eating mainly seeds later in life, insects are an essential part of the diet of growing Bobolinks. Here are some of the key benefits insects provide:
- High in protein needed for muscle growth and development.
- Provide essential amino acids not found in seeds.
- Packed with vitamins, minerals, and nutrients like calcium, iron, and zinc.
- Easier to digest than seeds for the young digestive system.
- Softer bodied insects can be eaten whole without chewing or hulling.
The abundance of insects on the breeding grounds enables Bobolink chicks to grow rapidly. The protein allows them to nearly double their body weight in just a week! Without the insect protein, they would not thrive at such a rapid rate.
Foraging Behavior
Bobolinks use various foraging techniques to find the insects and seeds they need:
- Gleaning – Plucking stationary prey like caterpillars from vegetation while perched.
- Hawking – Catching insects, such as flies, in mid-air.
- Ground foraging – Scouring the ground for fallen seeds and insects.
- Flock feeding – Foraging in large groups, especially during migration and winter.
Their ground feeding behavior consists of a distinctive “walk-and-peck” method. They walk forward at a steady pace, pecking the ground for food as they go. This allows them to cover a large area and maximize their seed intake.
Threats to Food Supply
Bobolinks depend on specific habitats like native grasslands and hayfields. Loss of these habitats due to development and changing agricultural practices can threaten their food supply. Some specific risks include:
- Conversion of hayfields to row crops reduces seeds.
- Earlier and more frequent mowing destroys nests and reduces insects.
- Grazing livestock can trample nests and young.
- Pesticides reduce insect diversity and abundance.
- Excessive drainage damages wet meadow habitat.
Protecting grasslands and supporting bird-friendly agriculture practices are important ways to ensure Bobolinks continue to have access to the essential food resources they need.
Conclusion
The diet of young Bobolinks is highly specialized to meet the needs of their rapid growth and development. Regurgitated insects provided by attentive parents supply the protein required for the chicks to grow and fledge. As they mature, Bobolinks gradually shift to eating a wider variety of insects they capture themselves. By adulthood, seeds become the primary food source along with some insects. Bobolinks have evolved adaptations like conical bills and brush-tipped tongues that allow them to readily exploit both insects and seeds across a variety of grassland habitats throughout their range.