The Mccown’s longspur is a small songbird found in the prairies and grasslands of North America. Their diet consists primarily of seeds and insects, which they forage for on the ground. In this article, we will take a closer look at the different food sources that make up the Mccown’s longspur diet throughout the year.
Seeds
Seeds make up the bulk of the Mccown’s longspur diet. They have a thick, cone-shaped bill that is well-adapted for cracking open and eating small seeds. During winter, they rely almost exclusively on seeds for sustenance. The longspurs forage on the ground for seeds from native grasses and agricultural crops. Some of their favorite seeds come from plants like needle grass, wheatgrass, foxtail, brome grass, and wild oats. The proportion of seeds in the diet increases in the fall and winter when insects are less abundant. Stocking up on seeds provides the energy and nutrients the longspurs need to survive the cold winter months.
Favorite winter seeds
Seed Source | Scientific Name |
---|---|
Needle grass | Stipa sp. |
Wheatgrass | Agropyron sp. |
Foxtail | Setaria sp. |
Brome grass | Bromus sp. |
Wild oats | Avena fatua |
The longspurs use their conical bills to carefully remove the nutritious seeds from the stalks and husks. They are able to swallow small seeds whole. For larger seeds, they will crack open the tough outer coating and extract the soft inner kernel. The longspurs efficiently harvest seeds from the ground cover by walking in a distinctive way – taking a few quick hops forward, stopping to grab seeds, then hopping forward again in a punctuated rhythm. Their unique foraging style allows them to comb through the grass to find scattered seeds.
Insects
Insects and other invertebrates make up the other major part of the Mccown’s longspur diet. They consume a wide variety of insects depending on seasonal availability. Some of their insect prey includes grasshoppers, crickets, beetles, flies, moth and butterfly larvae, spiders, ants, and bee and wasp larvae. The proportion of insects in the diet increases during spring and summer when insect numbers are higher.
Longspurs forage for insects while walking along the ground. They capture crawling insects like beetles, caterpillars, and spiders directly with their beak. For flying insects like grasshoppers or bees, they will leap up and grab them from the air. Parents feed captured insects to their nestlings during breeding season. The extra protein provided by insects helps ensure healthy chick growth and development.
Favorite insect prey
Insect Type | Examples |
---|---|
Beetles | Ground beetles, darkling beetles, leaf beetles |
Grasshoppers | Lesser migratory grasshoppers, clear-winged grasshoppers, band-winged grasshoppers |
Crickets | Field crickets, camel crickets, jerusalem crickets |
Caterpillars | Cutworms, armyworms, loopers |
Flies | Crane flies, stable flies, blow flies |
Bees and wasps | Mining bees, potter wasps, paper wasps |
The variety of insects eaten provides a good balance of nutrients for the longspurs. Caterpillars and larvae offer healthy fats. Crickets and grasshoppers provide carbohydrates. Ants and some types of bees/wasps can give a boost of protein. This nutrient-dense insect diet sustains the longspurs during the breeding season and while rearing chicks.
Other Foods
While seeds and insects make up the bulk of their diet, Mccown’s longspurs will occasionally supplement with other food sources:
Fruit: Longspurs may sometimes eat small fruits like berries if they are readily available. Items like juniper berries, buffaloberries, and wild blackberries provide extra carbohydrates and vitamins.
Grain: During winter, they will eat waste grain left over in agricultural fields from the fall harvest. Wheat, barley, oats, and rice grains add crucial calories.
Greens: On rare occasions, longspurs have been observed eating small amounts of leafy plant material. However, this makes up only a very minor portion of the diet.
Grit: They will ingest small pebbles and grit to aid with digestion, especially during winter when seeds make up most of the diet. The rocks help grind up food in the muscular gizzard.
Though they occasionally eat other items, seeds and insects make up over 90% of the total Mccown’s longspur diet. Their beak and foraging adaptations are specifically tailored to finding and eating these small food sources hidden amongst the grasses.
Diet by Season
The longspur diet shifts over the course of a year as food availability changes:
Winter: December – February. The diet consists of 90-100% seeds. Insects are very scarce. They mostly eat grass and weed seeds readily available in the ground cover. Agricultural seeds become important in cultivated fields.
Spring: March – May. The proportion of insects in the diet increases to 30-40% as insect numbers rebound. Beetles, caterpillars, ants, wasps, and spiders are widely eaten. Seeds still make up 60-70% of food.
Summer: June – August. The peak breeding season. 50-80% of the diet is insects to meet energy demands. Grasshoppers and other larger insects are heavily consumed. Seeds comprise the rest of the diet.
Fall: September – November. Insects decline to 20-30% of the diet. More seeds are eaten to build fat reserves before winter. The longspurs start concentrating on winter wheat fields.
Tracking these seasonal shifts shows how the longspur diet is finely tuned to take advantage of the most readily available food resources throughout the year.
Foraging Behavior
Mccown’s longspurs have several key adaptations that help them find food:
– Cone-shaped bill: Specialized for prying seeds out of stalks and husks. Also useful for capturing insects.
– Color vision: Helps spot seeds and insects against vegetation. Males have possible tetrachromatic vision to enhance mate selection.
– Hopping gait: Allows them to quickly move through grass while scanning for hidden seeds.
– Scratching feet: Rake through ground litter to uncover insects and seeds. Sometimes use feet to hold seeds in place.
– Ground foraging: Feed solely on the ground. Do not perch on vegetation or feed in flight.
– Gregarious in winter: Form large nomadic flocks that cooperatively seek out concentrated food patches.
– Cryptic plumage: Provides camouflage while feeding to avoid predators. Disruptive color pattern matches dry grass.
These adaptations allow Mccown’s longspurs to thrive on the vast open prairies and grasslands. The longspurs time their breeding cycle to take advantage of peak food availability during the summer months. Their digestive system is also adapted to an almost exclusively seed and insect diet.
Digestive System Adaptations
The Mccown’s longspur digestive system has several specializations for consuming a seed and insect diet:
– Small gizzard: Powerful muscles grind hard seeds and insect exoskeletons. Gizzard lining contains small grit and stones to aid breakdown.
– Short intestine: Digesta passes quickly through the digestive tract. Food particles have less time to be absorbed by gut lining.
– Rapid digestion: Compensates for faster passage rate to allow adequate nutrient absorption. Food is processed very efficiently.
– Large ceca: Paired blind pouches near the large intestine provide additional surfaces for water, salt, and nutrient absorption.
– Omnivorous enzymes: Produce a variety of carbohydrases and proteinases to digest diverse seed and insect diet. More versatile than specialist feeders.
Together, these adaptations allow Mccown’s longspurs to gain maximum nutritional value from the seeds and insects they eat. Their digestive system is specially equipped to handle the abrasive grit and hard-to-digest chitin contained in these food sources. The longspurs are well-designed to energetically thrive on their prairie diet year-round.
Drinking and Water Balance
Mccown’s longspurs get most of the water they need from their seed and insect diet. The seeds and bodies of insects contain a good deal of preformed water. In warmer months, the longspurs also obtain preformed water from succulent greens, fruits, and nectar. This dietary water allows them to survive without drinking frequently.
However, they do need to drink free water to maintain water balance, especially in drier conditions. Longspurs obtain drinking water from rainwater pools, dew droplets on vegetation, and edge water along small prairie creeks and ponds. Their kidneys are highly efficient at both concentrating urine and producing dilute urine as needed to regulate hydration. Respiratory water loss is mitigated by cooling surfaces in the nasal passages.
During bitterly cold winter weather, Mccown’s longspurs can survive for weeks without drinking by entering a state of torpor to conserve body water. They are remarkably good at retaining metabolic water and minimizing water loss. Accessing drinking water daily helps maintain condition, but they can endure periods of drought if needed. Like many prairie birds, the longspurs are well-adapted to the extremes of their grassland environments.
Parental Diet and Nestling Feeding
The Mccown’s longspur diet shifts when adults are raising nestlings. Chicks hatch in late May or June after an 11-13 day incubation period. Nestlings are fed almost exclusively insects for their first 7-10 days. Their optimal diet is made up of 65% insects, 30% seeds, and 5% miscellaneous. Chicks grow very rapidly and require high protein and fat levels provided by insects.
Common nestling foods include:
– Caterpillars: Abundant in early summer. High in fat and protein. darkling beetles, crickets, grasshoppers
– Grasshoppers: Adults will eat the bodies and feed legs/wings to chicks. Good calcium source.
– Ants: Males collect ants to present to incubating females. Also fed to nestlings.
– Beetles and larvae: Contain usable fats and proteins. Crunchy exoskeletons help strengthen hatchling bills.
– Moths: Caterpillars preferred but adults also fed to chicks.
– Spiders: Provide taurine and vitamin E. Help stimulate nestling immune systems.
The chick’s diet gradually shifts to more seeds as they grow. By two weeks post-hatching, the nestlings are eating mostly seeds. The seed diet helps prepare the juveniles for foraging independence. Fledglings leave the nest at around 16 days old and must find all their own food. The chick-rearing season coincides with peak insect availability on the prairie, ensuring adequate food.
Pesticides and Contaminants
The widespread use of pesticides and herbicides on agricultural grasslands poses some risks to Mccown’s longspurs through diet exposure:
– Insecticide accumulation: Chemicals like neonicotinoids can concentrate in insect tissues. Longspurs eating contaminated insects may be exposed to toxins.
– Herbicide contamination: Residues can wind up on grass seeds foraged by longspurs. Some compounds like glyphosate may negatively impact gut microflora.
– Soil ingestion: Loose soil is often accidentally eaten when longspurs pick seeds and insects from the ground. This can expose them to persistent organic pollutants in the soil.
– Biomagnification: Environmental toxins become more concentrated higher up the food chain. Longspurs may be especially vulnerable when eating lots of contaminated insects.
Because Mccown’s longspurs rely on such a specialized diet, they have little option but to eat whatever seeds and insects are available in their prairie habitats. Their risk of exposure depends greatly on agricultural chemical usage in the areas where they breed, nest, and overwinter. Consuming contaminated food could potentially impact longspur health and productivity. More research is needed on this pressing issue.
Conclusion
In summary, Mccown’s longspurs have a specialized diet consisting mainly of seeds and insects. Seeds from native grasses and agricultural crops provide the bulk of their winter nutrition. Insects like grasshoppers, beetles, and larvae offer extra protein during the breeding season. The longspurs have several key adaptations for finding and eating these small food items including a cone-shaped bill, hopping gait, scratching feet, cryptic plumage, and a digestive system tailored to this gritty diet. Their prairie habitats provide seasonally abundant seeds and insects perfectly aligned with their breeding chronology. However, pesticide usage may represent an emerging threat through dietary exposure. Understanding the details of the Mccown’s longspur diet gives key insights into their behavioral ecology and conservation needs. Protecting the integrity of their prairie food webs will be vital for ensuring the long-term viability of these declining grassland songbirds.