TRUST EVOLUTION TO give the males of many species an excuse not to stick around and help with the kids. "Life's overriding goal is to get your genes out there with a minimum amount of invested energy and time," explains Les Kaufman, an evolutionary ecologist at Boston University's Marine Program. "The female's role usually forces her to put much more time into the parenting process. So she's choosier selecting a mate to avoid wasting this time and energy. The male uses less energy but also has less control over whether his genes make it into the next generation. So he hedges his bets by mating as much as possible." It only follows that the males of many species have adopted a "love 'em and leave 'em" strategy. But some animal fathers have taken other paths--shaped by such factors as severe living conditions that require effort from both parents for the young to survive. Or unusual reproductive techniques like external fertilization (used by fish) that leave males the last ones present--and therefore stuck with the parenting duties. No matter the reason, various animal dads are out there plugging away and raising their young. Here's a Fathers Day recognition of 10 of our national best (unscientifically chosen, with admittedly human criteria)--as well as one winner of the worst-dad category.

1. BEST TOUGH-LOVE DAD

Red fox.
Photo: Charles G. Summers, Jr.
Long before the male red fox's love gets tough, he is an attentive, indulgent mate and father. For the first month after the birth of his young, his vixen must stay in her den, doubling as a food source and thermal blanket for their young. Dad's job is providing her with food every four to six hours until she can leave the den and start hunting as well. Researchers have seen fox dads exhibiting much excitement about their pups, playing with them endlessly. One father was even observed waiting for a watchful aunt to fall asleep and then quietly calling to his pups to come play with him. After three months, it's time for life's first harsh lesson: no more free meals. "Through years of observation, I've come to believe parents start reducing food as a tactic to get the pups moving away from the den," says David Henry, ecologist for the Canadian National Parks. "And it's the father that takes the lead with this strategy." Fox fathers don't just leave their young hungry, however, they help teach survival skills. They bury surplus food close to the den and disguise it with leaves and twigs. This technique, says Henry, teaches the pups to sniff and forage. Biologist Shelly Pruss (one of Henry's students) studied the closely related swift fox in a region where they were being killed by coyotes. There, she saw a male fox playing ambush with his offspring as if teaching them how to escape from predators.

2. BEST AMPHIBIAN DAD

Barking frog.
Photo: R. D. Bartlett
Truthfully, there is not much competition. The male barking frog in the U.S. Southwest is the only North American frog known to pitch in with parenting. His contribution? He stays near the eggs until they're hatched, wetting them down with urine when they begin to dry out.

3. MOST THOROUGHLY MODERN DAD

Wilson's phalarope.
Photo: Chuck Gordon
The phalarope takes role reversal to extremes. The male makes the nest, incubates the eggs and cares for the young. His breeding plumage is also less colorful than his mate's, almost unheard of in the avian world. In this country, northern and red-necked phalaropes nest in Alaskan tundra, and Wilson's phalaropes nest in inland marshes in the West.

4. MOST MULTIDAD HOUSEHOLD

Northern jacana.
Photo: Greg R. Homel
While a female jacana guards her territory from predators, her harem bustles with more domestic tasks: As many as four male counterparts are each building their nests and rearing their individual clutch of eggs. Usually found south of the U.S. border, these long-legged and long-toed wading birds sometimes range into Texas.

5. BEST FEMALE-IMPERSONATING DAD

The male seahorse doesn't have a real pregnancy (because in human terms, at least, then he would be a she), but it comes pretty close. In fact, according to evolutionary ecologist Sara Lewis at Tufts University, "Seahorses
Lined seahorse.
Photo: Herb Segars
are the champions of paternal care. They are one of the few animals where the males are morphologically specialized to take care of the young." Talk about role reversal. After an elaborate courtship that includes sunrise swims along the ocean floor, the female inserts a tube inside the male's brood pouch and "impregnates" him with eggs. While she swims off, the male knocks his body against a plant or rock to settle the now fertilized eggs in his pouch. Researchers speculate the lining of the male's pouch may function much like a mammal's placenta, helping supply nutrients and oxygen to the young. As these embryos grow (for 10 to 30 days depending upon the species), the male seahorse's belly swells great with child (actually, 10 to 300 offspring, depending upon the species). Come time for delivery, the seahorse doubles up to squeeze his swollen abdomen and pop out progeny. The process can take hours as the young spring free and clumsily swim to hook themselves on nearby grasses. The male will then go back to the same partner later that day to mate again. Seahorses can be found in all of the nation's shallow coastal waters.

6. DAD WITH THE BEST DIETING PLAN

Gafftopsail catfish.
Photo: John G. Shedd Aquarium
The male sea catfish's mouth is his nursery, as he swims around with jaws full of eggs the size of marbles, which he picks up shortly after the female lays them. This strategy precludes eating, so he lives off body fat for the month it takes the eggs to hatch and also for the two or three weeks his young need to grow into independence. Sea catfish inhabit temperate coastal and brackish waters in the northern Gulf of Mexico and southern Florida.

7. MOST MISUNDERSTOOD DAD

Giant water bug.
Photo: Edward S. Ross
While paternal care goes against the norm in the insect world, it also went against the grain of Florence W. Slater, the Victorian scientist who discovered that the male giant water bug shouldered his species' parenting burden: "That the male chafes under the burden is unmistakable," she wrote. "In fact, my suspicions as to the sex of the egg-carrier were first aroused by watching one . . . trying to free itself from its load of eggs." Slater's prejudice led her to misinterpret the behavior of the most conscientious bug dad, whose parenting stint begins with an elaborate courtship dance. "Unlike males in many other species, he tends to be more coy and cautious, and the female more aggressive," notes Randy Morgan, headkeeper of the Insectarium at the Cincinnati Zoo. Once they've mated, the female essentially glues her eggs on the male's back. "He'll be expending a lot of energy during this parenting process," says Morgan. "So after she lays some eggs, he insists they mate again to ensure his paternity." After he's loaded up with 150 or more eggs, the male water bug is totally responsible for them. He strokes the eggs-- not, as Slater thought, to dislodge them but to clean them. He executes a sort of deep knee bend to aerate the eggs. He sometimes sits at the water surface to dry them off and get rid of parasites. Mostly, however, "he takes advantage of having his eggs mounted on a mobile unit and moves around to escape predators," says Morgan. Observant naturalists in the southwestern United States and Florida can see these behaviors in and near moving water at higher elevations. Within a few weeks, the eggs triple in size. Right before they hatch, the male stops eating to avoid consuming his offspring. Once his young hatch and scatter, the male ends his parenting session by kicking the egg pads off his back--this session anyway. He can have three more clutches before breeding season is over.

8. MOST SELF-SACRIFICING DAD

Pacific spiny lumpsucker.
Photo: Jeff Foott
When the tide's in, the lumpsucker (a stout-bodied, tadpole-shaped fish found in our northern coastal waters) isn't much different from other fish dads that aerate their eggs by fanning them with fins or tail. When the tide recedes, however, the lumpsucker goes the extra mile by staying put. He remains with his eggs by attaching himself to the rocks with a sucker formed from his pelvic fins, a kamikaze move exposing him to hungry gulls and crows.

9. HARDEST WORKING DAD

Great horned owl
Photo: E. R. Degginger
He starts by establishing his territory and attracting a mate with his "three or five hooter" call. Then, since his own species has no architects or builders, both partners must go househunting for places like old squirrel nests, hawk nests or hollowed-out tree stumps. "I've even seen an owl take over a red-tailed hawk's nest," says ornithologist Richard J. Clark at York College of Pennsylvania. In late winter, the female lays her two or three eggs and the male's marathon begins. While she keeps those eggs from freezing, he brings home the bacon (or, in the owl's case, rats, mice, squirrels--and even prey as large as pheasants). In most bird species, says Clark, the female is the smaller animal, but not birds of prey. So the male great horned owl must feed himself and another adult about 25 percent larger than he. With two or three hatchlings crying for food, his burden multiplies, especially since the mother is caring for owlets that can't maintain their own body temperature for the first days or weeks of life. After about a month, however, she starts to help hunt. It's a good thing too; the fledglings will grow bigger than their parents and require as much as one-fourth their body weight in daily food intake.

10. BEST BACHELOR-PAD DAD

Threespine stickleback.
Photo: Tom McHugh
In spring, the male threespined stickleback gets domestic; but to become a homebody, he must build a home. Using twigs, plant debris and mucus as mortar, the resident of northern U.S. waters and the eastern North Pacific meticulously constructs bower-like nests. "It's wonderful to watch," says Boston University's Les Kaufman. "He backs up and stares at the nest like an artist, then swims over to make adjustments. He'll add a stick or two, spitting water to move them into place." Once satisfied with his creation, the stickleback turns to finding a mate. Advertising availability with a bright red belly and blue-green on his tail, he approaches a female and vibrates to signal his interest. To capture hers, he shows off his prime real estate. The process continues until a female enters his nest to lay eggs. Her role done, the male chases her out and swims through the nest to fertilize what she has left behind. Then he may add to his brood by repeating the process with other females. "Everybody's out for themselves here, working to pass their genes on," says Kaufman. "Females eat the eggs of their competitors. And a male eats eggs if he didn't end up liking the female who laid them. Or if he gets too hungry." Once he moves on to guarding his nest, the stickleback is a protective dad. He fans oxygen-filled water to the eggs with his fins. He removes eggs infected with fungus. He defends his young fry, which remain in the nest for a few days to feed on their still-attached yolk. And he gathers wanderers in his mouth and spits them back into their nursery until they're ready to be off on their own.

11. WORST DAD

Grizzly bear.
Photo: G. C. Kelley
Deadbeat dads who desert their young are bad enough, but the grizzly bear actually kills cubs. To be fair, the grizzly is an equal-opportunity assassin. He goes after any cubs in his home range, an area as big as 1,200 square miles, where a half dozen females could be rearing young. "There's a good chance he's killing his own offspring," says biologist Harry Reynolds of the Alaska Department of Fish and Game in Fairbanks. A murderous male doesn't find it easy to get past mother bears, however--despite the fact that he is likely two or three times bigger than they are. Females with cubs are ferociously protective, and the more aggressive the female, the more likely she'll succeed in protecting her young. "This characteristic has obvious evolutionary advantages and may in part explain the species `personality' traits," adds Reynolds. Killing progeny seems counterproductive, evolutionarily speaking, so why does the grizzly practice infanticide? According to biologist Vic Barnes at Alaska's Kodiak National Wildlife Refuge, murderous males may be regulating the size of the bear population. Since females can have litters of mixed paternity, another theory suggests a male kills cubs so a female will come back into estrus and he can impregnate her again to better ensure passing on his genes. To Reynolds, neither theory seems conclusive. "Here's one thing we do know," he says. "Bears are successful because they are opportunists, eating anything from grasses to whale carcasses. If that food source is occasionally another bear, I doubt they stop to think about it."