Expectant Fathers

Lesson 7: Pregnancy and Nature

If Only Your Partner Could be a Sea Horse

Another wonderful parent reversal is seen in the Three-Spined Stickleback. This colorful fish is frequently seen as the brilliant afternoon sun beams down on the New Jersey Lake. As the days grow longer and warmer in summer, the tiny three-spined sticklebacks are camouflaged by their blue and silver colors. Various hormones in the fish cause males to change colors to attract a mate. Normally silver-colored on the underside, they turn a brilliant orange-red, acting as a STOP sign for passing females.

Both males and females swim toward the warmer water near the shore of the lake when it is time to male and each male selects a sandy place for itself in the quiet, shallow water.

While defending his territory, the male stickleback goes to work building his nest by whisking out a smooth, sandy pit with his pectorals, or bottom fins. For the next three days he collects bits of algae and shapes them into “a one bedroom no bath” nest. After gathering enough algae, the male swims back and forth over his new apartment, releasing waterproof glue produced by his kidneys. This glue holds the nest together. As it’s completed, the little fellow swims straight through the middle to assure that there is a tunnel that is open at both ends. Just an inch or two long, the nest tunnel is now ready for a female to enter and lay eggs.

When a possible mate approaches, the male does a zigzag courtship dance similar to Michael Jackson’s famous moonwalk. If the female believes the dance worthy and is ready to lay her eggs, she swims inside his nest and deposits three or four whitish eggs. The male then nudges her out as he swims through the nest and fertilizes the eggs, no conversation, no final cigarette, not even the promise of another encounter. For the next day or two, the male continues to attract other females to lay more eggs in his nest.

Mother sticklebacks produce dozens of eggs so females may enter more than one nest and only leave a few eggs with each father. The eggs have a yolk with sufficient nourishment to last a few days before the fry hatches. Once a mother stickleback’s job of egg laying is done, she doesn’t return to any of the nests or see her young again.

The father stickleback, however, has more work to do. Besides nest building, his job is to watch over the eggs. For two weeks, the male guards his nest fiercely. He fans oxygen-filled water through the tunnel with his fins and repairs any damage to his temporary home. Protecting this nest is a full-time job so he doesn’t leave the nest, even to eat. If a hungry fish approaches, the father stickleback swings the spines on his back like a sword and bites the intruder to chase it away. Even females are chased away by the male now that he’s on permanent guard duty.

At last, hatching day arrives. The first of the fry, or hatchlings, breaks out of its egg. As the babies hatch, the father tears away the threads of algae that cover the nursery and prepares announcement cards. The tiny hatchlings stay together in the nest for a few days and because the yolk attached to each baby’s body is still providing food, the young fish don’t need to eat. If one of the fry straggles away, the ever-watchful father grabs it with his mouth and spits it back into the nursery.

After a few days, the male stickleback no longer has the energy to guard the nest so carefully. But by now the hatchlings are ready to be on their own. One by one, they leave their sandy haven. Of course they go on to school, but Dad skips out on paying college tuition.

There are other fish with the same paternal pattern as the wonderful little stickleback. The male sand goby, a fish living in the waters off the coast of France, builds the most attractive nest possible with the hope of luring desirable females. The goby searches for an empty cockleshell with which he begins construction of his future dwelling. He turns the shell over so the concave side is facing down and excavates the sand from underneath. Next he heaps some of the sand on top, leaving only a narrow channel for access. When the nest is ready, with attractive decor, lighting, and mood, he escorts a female to it and waits outside while she demurely slips in and deposits her eggs. Tapping his Mermaid watch impatiently, he waits outside for her to leave. Once she’s gone, the time is right for his fertilizing the eggs. Days pass while he stands guard and makes sure the fry hatch, completely confident that no sperm other than his could have done the job.

Next up the species chain may be birds. One of the largest and most familiar to the Nature Channel is the penguin. The male Emperor Penguin is entirely responsible for incubating his mate’s one precious egg over the long Antarctic winter. This is done inland while the female returns to the sea to feed. His success depends entirely on his fat stores; if a male gets too thin, he will abandon his egg and try to get back to the ocean. Big fat males are consequently creatures of great worth and females will vigorously fight over them. Once the egg hatches, the male produces milk from a gland in his esophagus to feed his chick; no nursing bra required here!

Another parental role reversal occurs for the Spotted Sandpiper. These are one of the few species of birds that are sex-role reversed, like the Jacana previously mentioned. Female sandpipers are aggressive and play the more active role in courtship, while males provide most or all of the care for the young. Studies of the birds’ hormones have shown that males have a sharp reduction in testosterone and higher levels of prolactin than females – particularly after a clutch of eggs has been laid. Males will diligently sit on the eggs for a 21-day incubation period and tend the fledglings for another 21 days. Females may offer some assistance if the clutch is her last of the season, but generally she is quick to shirk her duties if an opportunity arises to take another mate!

“Are you a man or a mouse?” is an old question used to challenge a guy’s manhood. However, certain mice have an endearing way of handling their paternal-domestic duties. Deer Mice dads, for example, immediately pitch in postpartum by guarding their young when the female goes off to feed. Males have been observed hovering over their young, surrounding them with nesting material, and even washing them. Studies of rodent species have shown that pups reared in the company of both parents survive better and grow faster than those reared only by the mother.

The final example of mammal dads stepping in is the male Red Fox. He is a devoted mate and father. Not only does he supply his vixen with fresh food every four to six hours while she nurses her pups, but he is equally dedicated to teaching his offspring survival skills. Males will bury food near the den to train pups how to sniff and forage and will play ambush games with them to teach self determination and defense. Unusual in nature, the Red Fox (the animal not the comedian) is a model for fathering.

Kids Keep a Dad Younger While He Gets Older

Did you know that women in the United States on average outlive men? Although this is sometimes thought to be a recent phenomenon, rooted in improvements in medicine that make childbearing less risky, Swedish mortality records going back to 1780, long before modern medicine, show that women lived on average 5 to 8 percent longer than did men. In a study of ten primate species, including humans, apes, and various Old world and New World monkeys, researchers have shown that the parent that cares for the offspring typically lives longer than the mate, regardless of gender. And, the mother is not always the primary care giver!

The male Titi monkey of South America, for example, who takes care of the baby after the mother has given birth, outlives his mate by 20 percent. In contrast, female chimpanzees and orangutans who are the sole caregivers, live significantly longer than their male counterparts. In captivity, female chimpanzees live on average 42 percent longer than do males. In the world, three times as many females as males are found in natural groups, reflecting their greater survival rates.

This pattern is reversed in such species as the Siamang Apes, who pair-bond. Siamang males are unique among apes in the intensity of their bonding with their offspring, who they carry from the second year on. Male Siamang apes live 9 percent longer than their female counterparts.

Researchers working in this area conclude that this gender-specific enhanced survival is the result of a complex blend of reduced risk taking and reduced vulnerability to stress, which may be mediated by the hormonal effects of parenting. Researchers find that testosterone levels are reduced during pregnancy for most male mammals, including humans. Former levels are restored during the postpartum period. In humans this usually takes three to six months.

Although there are exceptions to this by species and individual, prolactin, which is generally known as the hormone that stimulates milk production in new mothers, increases during this same period for males. It’s believed that this may reduce male aggressiveness during pregnancy and produce the more nurturing attitude often seen in expectant and new fathers. (It may also be responsible for the soft, gentle manner of grandfathers since testosterone levels decrease and prolactin levels increase as men get older.) Prolactin is related to nesting and nurturing activity and is the reason male penguins and both male and female pigeons produce crop milk, a sort of “non dairy creamer” that nourishes their young.

Prolacin sometimes encourages nurturing behavior in new fathers, it rarely stimulates milk production in male mammals, but there are exceptions. In rare cases, when the milk-producing apparatus has been exposed to higher-than-normal levels of estrogen and progesterone, prolactin can stimulate milk production in males. A particular biologist describes the case of a Scottish goat named Claymore. Claymore was a remarkable goat with an extraordinarily high prolactin level. Being male didn’t interfere with his ability to produce milk. In fact, he liked his own milk so much that he would sometimes nurse himself in the barnyard. He also provided enough milk for the production of goat milk cheese.

So nature provides us with a great lesson: there are few “norms” in what we otherwise consider normal. For many creatures, including us, fathers assume a nurturing role. In the animal and insect examples presented, fathers are responsible for everything from being the recipient of courtship, to delivery of the young and childcare. You may want to share some these examples with your male partner as you whisper in his ear, “You’re such an animal!”

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