The Plant-Caterpillar-Bird Connection
In spite of the common saying, “The early bird gets the worm,” very few bird species will actually feed their young worms! Instead 96% of North American terrestrial bird species opt for insects to rear their young, and the most common insects they choose are caterpillars or adult moths. One single medium-sized caterpillar is as good as 200 aphids and contains twice to three times the amount of carotenoids as most other insects.
Caterpillars are very simple to find as they like to hang out on the leaves of plants, and their mushy bodies with thin exoskeletons makes them easy for baby birds to digest. They are also very high in protein, fat and carotenoids, the latter of which are especially important for birds due to their ability to improve color vision, stimulate the immune system and provide colorful feather pigmentation.
A typical nesting period for a bird is 16 days, and birds will lay between 2-10 eggs per clutch depending on the species. Each individual baby bird needs to eat a full meal between 30-40 times per day, so during the fledging period mama and papa bird will make several hundred trips back and forth to the nest bringing in caterpillars for their babies. This is why birds will try to only build their nest in a well-defined territory with lots of available food. A bird that needs to fly a mile out every time food is needed will quickly tire out and never be able to meet the demand from its babies.
By the end of the fledging period, thousands of trips have been made just for one single bird’s nest. Can you imagine the number of caterpillars needed to sustain multiple species of birds for just one park? If a person wanted to see warblers, robins, woodpeckers, buntings, yellowthroats, sparrows and cardinals in their neighborhood, what kind of environment would need to be present in order to sustain all those nests?
The best way to accomplish this task is to use plants that serve as hosts for as many caterpillar species as possible. Fortunately, entire databases have been created to answer this question (https://nativeplantfinder.nwf.org/) and for St. Cloud Florida our top five host trees and shrubs are:
Oaks (395)
Rosales Prunus - plums, cherries, peaches, etc. (247)
Hickory (191)
Willow (190)
Maple (171)
And our top five flowers and grasses are:
Goldenrod (82)
Sunflower (58)
Hibiscus (37)
Cowpea (35)
Baccharis (31)
Without keystone plants like these, the food web and all the wildlife that depend on it falls apart. The most productive landscapes have an abundance of native keystone species.