Mimic Makers
Biomimicry, which refers to innovations by humans that are inspired by nature, happens to be one of my favorite topics, and I particularly love introducing the concept to children. Occasionally I come across a natural history book which is so compelling that I want to share it with Naturally Curious readers, especially at a gift-giving time of year. Mimic Makers: Biomimicry Inventors Inspired by Nature by Kristen Nordstrom is one of these books.
Written for elementary school readers, it engagingly presents ten “mimic makers” who come up with technological inventions based on the natural world (leaf-inspired solar panels, beetle-inspired water collectors, maple seed-inspired drones, etc.). It’s biomimicry at its very best, guaranteed to captivate young (and not so young), inquisitive minds. (Photo: Red Maple seeds/samaras)
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Red Maples Flowering
Red Maples (Acer rubrum) are celebrated in the fall for their vibrant foliage, but they produce equally vibrant reds and yellows in early spring when they are flowering. Most Red Maples have dense clusters of either male flowers or female flowers (dioecious). Under certain conditions, a Red Maple tree can sometimes switch from male to female, male to both male and female (hermaphroditic), and hermaphroditic to female.
The showier male, or staminate, flowers contain between four and twelve stamens, with long, slender filaments and red (young) or yellow (mature) anthers at their tips. Both red sepals and petals can be seen at the base of the stamens. A staminate Red Maple in full bloom is a blaze of gold and red. (Photo: mature staminate Red Maple flowers)
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Maple Leafcutter Moth Larvae Descending
This time of year it looks like someone has visited every other Sugar Maple (and to a lesser extent, Red Maples and birches) leaf with a hole punch. The Maple Leafcutter Moth (Paraclemensia acerifoliella) is the hole-punching culprit. At the beginning of the summer, leafcutter larvae hatch and begin mining tissue between the upper and lower layers of maple leaves. The mines are barely discernible, as the larvae are so small at this stage. A bit later in the summer the larvae start using their mandibles to cut out round discs of leaf tissue. They take two of these discs and fasten them together with silk, forming a protective case around themselves as they consume additional tissue between the leaf veins. It is this feeding that causes the “punch holes.” As the larva grows, it cuts larger and larger discs to form its case.
When September comes, the larvae are mature and descend to the ground, carrying their homes with them as they move into the topsoil to pupate. Orange-headed, metallic blue-winged adult moths will emerge in the spring, leaving their leaf homes behind.
Because leaves have produced most of the sugar they are going to produce by late summer, the feeding behavior by the moth larvae that occurs from August until leaf fall isn’t a threat to the health of the tree unless complete defoliation occurs for three consecutive years or more.
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White-tailed Deer Scent-Marking
Scent-marking plays an important communication role in the animal world. A variety of species use glandular secretions to convey (for some distance) messages. From beavers spreading castoreum on scent mounds to fishers leaving their scent every time their hind feet touch the ground, the woods are alive with messages often undetected by most humans. Some of these are left by White-tailed Deer, which have two primary scent-marking behaviors: antler rubbing and scrapes.
One used to associate an antler rub with the act of a buck removing drying velvet from its antlers. However, it turns out that very few rubs are made by deer removing antler velvet, a process that’s normally completed within 24 hours. Instead, most rubs are made by relatively few dominant bucks to signal their readiness to breed and to mark their territory.
All White-tailed Deer possess specialized forehead glands that become increasingly active in autumn, particularly in adult males. All bucks spread their scent by rubbing their foreheads (which contain specialized scent glands) against trees and shrubs that have smooth bark, few, if any, lower limbs and are ½” to 4” in diameter. (Older bucks also will rub trees six or more inches in diameter.) In the Northeast, Trembling Aspen, Staghorn Sumac, Red Maple, and willows are often used for this purpose.
Mature, socially high-ranking bucks exude greater amounts of the glandular secretion than do younger males or females. They begin marking their territory soon after losing velvet and continue marking until they cast their antlers in December or January. The chemical signals left at a rub site tend to suppress the aggressiveness and sex drive of young males. However, those same signals stimulate females. The amount of rubbing an individual buck does depends on the level of testosterone in his blood, which in turn is largely determined by the animal’s age and dominance status.
We may not be able to detect the chemicals on a rub, but it’s hard to miss the sight of the light-colored blazes that magically appear in the woods at this time of year. (Photo: White-tailed Deer rub on Staghorn Sumac. Thanks to Chiho Kaneko and Jeffrey Hamelman for photo op.)
Red Maples In Bloom
Red Maples (Acer rubrum) are celebrated in the fall for their vibrant colors, but they produce equally vibrant reds and yellows in early spring when they are flowering. Most Red Maples have dense clusters of either male flowers or female flowers (dioecious), although some have both male and female flowers (monoecious). Under certain conditions, a Red Maple tree can sometimes switch from male to female, male to both male and female (hermaphroditic), and hermaphroditic to female.
The showier male, or staminate, flowers contain between four and twelve stamens, with long, slender filaments and red (young) or yellow (mature) anthers at their tips. Both red sepals and petals can be seen at the base of the stamens. A staminate Red Maple in full bloom is a blaze of gold and red. (Photo: mature staminate Red Maple flowers)
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Yellow-bellied Sapsuckers Have Varied Diet
Yellow-bellied sapsuckers are just starting to arrive on their northern breeding grounds. As you might assume from their name, these birds feed on the sap of trees. Their horizontal lines of drilled holes are a familiar sight, especially in trees such as paper birch, yellow birch, sugar maple, red maple and hickory, all of which have a high concentration of sugar in their sap.
In addition to sap, yellow-bellied sapsuckers also eats insects (primarily ants), and spiders, probing underneath bark to find them. They’ve even been observed “hawking”– taking off from a branch and scooping up insects in the air.
Lesser known is the fact that sapsuckers also consume vegetation, including the inner bark and cambium layers of trees, the buds of trembling aspen, and a variety of fruits and seeds. The recent cold snap had the pictured male yellow-bellied sapsucker scarfing down crab apples before the sun set. (The next NC post will be on 4/11/15.)
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Red Squirrels & Sugar Maples
We’re approaching what is often a very stressful time of year for many animals, including red squirrels. In the fall they feed on all kinds of conifer seeds, mushrooms, insects, nuts and the many fruits and berries that are available. They also have caches of cones, which they turn to once there is a scarcity of food elsewhere.
Once these caches are used up, usually by late winter or early spring, red squirrels turn to sugar maples for nutrients. Their timing is perfect, for this is when sap is starting to be drawn up from the roots of trees. Red squirrels are known to harvest this sap by making single bites into the tree with their incisors. These bites go deep enough to tap into the tree’s xylem tissue, which is where the sap is flowing. The puncture causes the sap to flow out of the tree, but the squirrel delays its gratification. It leaves and returns later to lick up the sugary residue that remains on the branch after most of the water has evaporated from the sap.
Not only do red squirrels help themselves to sugar maple sap, but they have developed a taste for the buds, and later in the spring, the flowers, of both red and sugar maples. Red squirrels are not the only culprits – gray squirrels and flying squirrels also make short work of buds and flowers from these trees.
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