Cannibalism

©Terry R. Thomas/www.nature-track.com

African lion males are notorious for killing and eating the young of their rivals when they take over a pride of lionesses.

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During this time of thanks and gratitude, I think I need to thank my two older brothers and my dad for not eating me. This is a real thing, called size-structured cannibalism (where populations are made up of different ages of individuals) where, “older, larger, more mature individuals (dad and two older brothers) kill and consume smaller, younger conspecifics (me).”

I got to thinking about this when something jarred a memory about the controversial disappearance of Michael Rockefeller (son of Nelson Rockefeller, Gerald Ford’s vice-president) in Borneo in 1961. While the official family story is that Michael drowned after trying to swim to shore following a boating mishap, there are many local stories of how Rockefeller made it to shore and was killed and eaten (the tribes in this area were headhunters and still occasionally practiced cannibalism) in retribution for the killing of five natives by Dutch government officials in 1958.

We find cannibalism to be appalling and readily re-tell and debate stories of ill-fated travelers like the Donner Party (October 1846 to April 1847, 45 of 89 survived) and Flight 571 (that crashed in the Argentinean Andes in 1972 with an entire rugby team and families—16 survived the 72-day ordeal), where cannibalism (but not murder) played a role in the continued existence of survivors.

However, in nature, cannibalism is not an abnormal behavior. At least 1,500 species have been found to practice cannibalism, usually including the killing of the conspecific (which means same species).

This is particularly true in the invertebrate world. Dragonfly nymphs suffer a 95 percent mortality to their older and larger siblings (size-structured cannibalism again). Ant colonies often eat their young during periods of stress and the list could go on and on.

Sexual cannibalism is practiced by many spiders, but also species of other classes, praying mantises, for example. Sexual cannibalism is where the male pays with his life in order to breed, being consumed by the female, often while in the very act of copulation. In fact, that is where the black widow spider gets her name.

As a twist, there are some species of spiders where the mother sacrifices her own body for the developing young. Called matriphagy, a velvet spider, for instance, dissolves her own organs and spits them up for her newly hatched young to feed on. Eventually, they consume her in entirety, assuming a male doesn’t find and eat the youngsters first.

There are some scientific theories as to why animals perform sexual cannibalism. Several center around the nutritional level of the female and the boost she may get from this meal just before laying eggs, improving their chances of surviving.

To me, cannibalism in the lower orders seems to make sense on a more visceral level. Anything that moves is potential food and they may not even be able to distinguish their own species in many cases. In my humble opinion, there may not be an ecological reason for it other than food is food. However, after watching a National Geographic video of a leopard eating another leopard, I may include the higher orders in this as well.

But even among the vertebrates, cannibalism is not uncommon. When we kept hamsters, the male went missing one day and we assumed that it had escaped. When we cleaned the cage though, we found what little remained of him buried in the corner. Hamsters are also known to consume their young if disturbed.

King cobras, giant snakes from Asia (up to six meters long) are snake-eating specialists. Since other cobras are snakes, they are on the menu as well. The king cobra just wants to eat and if that meal is another king cobra, so be it.

It is well-known that among bears and African lions, adult males will prey upon the young of other males, to reduce the competition from other males and to bring the females back into estrous more quickly.

What is less well known is that our closest primate relative, the chimpanzee, will do the same thing. Adult males will raid other troops and kill and eat the infants that they catch. Even our cute little red squirrel males will practice this infanticide/cannibalism.

There are some instances where cannibalism is useful in controlling population levels. This has been noted in aquarium guppies, for instance. It seems that overcrowding can spur cannibalistic behavior.

While we may consider cannibalism abhorrent, in the natural world, it seems to be more normal than not. It is literally a dog-eat-dog world out there and in the final analysis, protein is protein. Just don’t tell that to your big brother.

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Help Idaho Wildlife

When we traveled across the state in October 2017, most of the vehicles we saw using the wildlife management areas did not have wildlife plates. Buying wildlife plates is a great way for non-hunters and hunters alike to support wildlife-based recreation like birding.

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! 

See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

And tell them that you heard about it from Nature-track.com!

Wildlife License Plates

Great news! as of 2024, there are three NEW designs for license plates. They still are bluebird, cutthroat trout and elk, but they are beautiful.

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program.

I think it is time we let the Legislature know that Idahoan support wildlife funding and that we would like to see these generic plates come to fruition.