An Unusually Excellent Mother

Sorry about the gap between posts! I had to take a break to wrap up my undergraduate career… I am now a Humboldt State University graduate, with a degree in Wildlife Biology! Yay! That means everything on here is legit, straight from a real biologist, right? Right. We’ll go with that. This one’s extra long to appease you after the long break.

I want to talk about moms. Because I really like mine, and there are some pretty incredible ones in the animal world too.

Mother’s Day was a few weeks ago, and I was far from home, in eastern California looking at birds. After a weekend of camping, getting up at 5am, chasing crazy birds, and sleeping cold, I had mostly forgotten about the holiday. But on Sunday, somewhere between Lava Beds National Monument and Tulelake, I saw something that reminded me: a great horned owl mother and her chick, sitting on a rock face soaking up some sun (I am assuming this is the mother, as the females do most of the parental care). The fluff ball of an owlet was significantly smaller than mom, and snuggled right up next to her. As moms go in the animal world, most birds can be pretty fantastic, especially those with altricial young – those chicks that hatch naked, blind, featherless, and helpless (the opposite of this is precocial, those that hatch almost fully developed. Although there are species that fall between these two; it is a sliding scale rather than two exclusive categories). Mom (and sometimes dad!) will supply food to them until they grow their feathers and fledge from the nest. This is the case with great horned owls. The time and energy constraints placed on parents during this time of caring for young is one of the most strenuous periods a bird will ever experience as they are almost constantly searching for food for their young.

Many of us have seen bird nests and/or the iconic image of a mother bird feeding her chicks. It is not surprising to us, for some reason, that birds and mammals invest so much time in their offspring. They are warm-blooded like us, fluffy or feathery, and charismatic. We identify with the parents of these groups, and by this association, we assume their excellent parenting skills.

But there is an unsung hero in the world of animal mothers.
An unlikely mother, fiercely protective and unexpectedly gentle.
She has neither feathers nor fur, and relies on the sun to heat up her blood.
In her prime, she can reach nearly 20 feet.

She is a Crocodilian, and she will literally tear you limb from limb if you threaten her offspring.

Reptilians are not usually known for their parenting skills. We know they lay eggs and many may guard the eggs until hatch time, but most exit the story after that. Crocodilians – members of the Order Crocodilia including crocodiles, alligators, and caimans – are an exception. Not only do they build extravagant vegetation nests for the eggs, they stay around long after hatch. First off, let’s talk about that nest some more……

Eggs need to be warm to develop properly. Birds sit on their eggs to keep them warm. Turtles bury them in sand to keep them warm. Most crocodiles and alligators build up large mounds of vegetation around their clutches to keep them warm (a clutch is a single group of eggs in a nest). Mom will adjust, shift, or add to the vegetation nest as needed throughout the course of incubation – the embryo development within the egg under the proper conditions – in order to maintain a temperature suitable for development. While there is a range of temperatures that the eggs must stay within in order to survive, curious things happen at different temperatures, specifically about two-thirds of the way through incubation: the sex of each embryo is determined at this time depending on temperature. All Crocodilians are subject to this temperature-dependent sex determination during incubation. The patter goes as follows: on the extreme ends, very warm and very cool temperatures will produce female offspring. In the middle, mild temperatures, male offspring are produced. Exactly why or how this works is not known (though there are many hypotheses).
Now, you may be thinking, “So are entire generations of crocodiles and alligators completely male or female? Are extreme weather patterns skewing sex ratios of Crocodylians?? OH GOD IS GLOBAL WARMING CREATING A SUPER RACE OF FEMALE CROCODILES?!?!?”
Settle down. No. That’s not happening (yet). Nature has this cool way of dealing with stuff like this; it’s called variation in nature. Because females will lay eggs in very different areas with different environmental conditions and varying weather patterns, natural populations tend to balance themselves out. No two nest sites are the same, and temperatures will vary among them, and even within them, creating a mix of males and females (but just to be on the safe side, let’s try not to add to climate change problems, mmmkay?).

Now on to the fun momma part! A couple months after laying eggs and keeping them at the perfect temperature, the baby crocs begin to pip – or crack the shells of their eggs from the inside out with the help of a specialized “egg tooth” which is actually a hardened bit of pointy skin on the end of their snout (these disappear shortly after hatching). Hatching is hard, you guys. Imagine being stuffed inside a tiny, hard space within which you’ve never really been able to move around. Suddenly, you need to get out. You gotta breathe! But you’re so tiny, and the shell around you is so tough to break through! What do you do?? You do what comes naturally of course. YOU CALL FOR MOM.

Crocodilians are some of the most vocal critters in the herpetological world. They are able to make a stunning array of sounds with a wide variety of purposes and meanings. And it all starts with little throaty chirping noises during hatching. This noise is a trigger for mom. She immediately heads to the nest upon hearing it, and begins to excavate the nest ever so gently. Moving aside the vegetation, the eggs come into view. Some have tiny snouts poking out already – the stronger hatchlings already making headway. Others need help though; some may have barely pipped, and show only small cracks on the outside of their eggs, but mom can hear them chirping even inside their eggs.
This is where it gets even more amazing than it already is. This is where one of the most feared, revered, and terrifying predators acts in the most gentlest of ways.
Crocodiles are known for having the strongest recorded bite force of any living animal, able to administer 3,700 pounds per square inch (psi) of bite force. Big cats can bite up to 1,000 psi. Humans around up to 200 psi. These are serious jaws with unrivaled strength, and momma crocodile will now use them to help hatch her eggs.

So very gently, she will take an egg in her mouth and carry it to the nearest water. Slowly she bites the eggs, with delicate pressure, in order to facilitate hatching. She will do this for as many eggs that need help, one by one, making sure the young are safely in the water. A baby crocodile or alligator on land is a vulnerable one, exposed to a variety of predators, and it is important that the hatchlings reach the safety of their aquatic nursery as quickly as possible. For the young that were able to hatch themselves in the nest, mom will carry them in her mouth to the waters edge, again demonstrating the grace and delicacy her mighty jaws are capable of.

Her care still does not end here. Young crocodilians will stay with their moms for several months to several years, depending on the species, relying on her presence for further protection. Instances of mothers “feeding” their young have even been recorded, albeit infrequently (see this cool video!!! 

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Tip your hats to the unexpected crocodilian mothers of the animal world. They are so much more amazing than anyone expected a “cold-blooded” mother to be, showing the utmost care and gentleness toward her offspring. Go hug your mom. She’s done a lot for you too. And remember that mammals aren’t the only ones capable of amazing motherhood.

Until next time friends. Respect those crocs, and especially their babies, lest you have a run-in with their mom.
Also watch this video, narrated by none other than the amazing Sir David Attenborough, which gives a wonderful visual to everything I just explained. I didn’t make it up.