Photos from Cape May, NJ

15 07 2007

Sunrise

Yesterday, my wife and I left at 3 AM to arrive at the most southern point/beach in New Jersey, arriving just after the sun began to rise.

Sunrise

And here is my lovely wife in the early morning light;

Tracey

We also encountered some local wildlife before even setting foot on the beach or pathways along the dunes. Many birds rested in their large birdhouses, and a small toad sat on the bench outside the restrooms;

Birdhouse

Lighthouse

Toad

Once we set foot on the beach, there were already plenty of Laughing Gulls skittering about on the sand and trying to snatch some bait from early-bird fishermen;

Laughing Gull

Tracey and I also noted a strange blob bobbing about in the surf. It turned out to be a dead jellyfish;

Jellyfish

We saw many more of the decomposing cnidarians on the beach that morning;

Jellyfish

After taking a little snooze on the beach, we took a short walk on a path behind the dunes, watching an immature Great Blue Heron and an egret try to catch their breakfast;

Egret

Heron

Small rabbits also abounded along the shore, and we saw many over the course of the day;

Rabbit

Being that it was too early to head over to the docks for our whale watching tour, we stopped by the Nature Conservancy migratory bird refuge. While most of the birds were too far away or simply not present during our visit, I did spot a number of Red-Winged Blackbirds, and this particular fellow was especially robust and colorful;

RWBB

This bright flower also caught our eye;

Flower

By the time was had walked the trail it was time for our cruise, although nothing much happened for the first hour or so (outside of being followed by some laughing gulls);

Laughing Gull

The whole trip did not turn out to be a wash, however, as we came across a rather large pod of Bottlenose Dolphins (15-20 individuals) feeding close to shore, right in front of one of John Wyland’s famous “Whaling Walls” (depicting a Humpback Whale, amongst other marine life);

Dolphins

Dolphins

After the overall mediocre cruise and stopping for lunch, we headed to the Cape May Zoo, where I finally got to see some live Pronghorns (previously the only ones I had seen were the stuffed ones at the AMNH);

Pronghorn

Pronghorn

And, of course, no zoo trip would be complete without seeing a Muntjac;

Muntjac

untjac

While I had seen Capybara in zoos before, I at long last got to see one swimming, as well;

Capybara

Capybara

As would be expected, the American Alligators were also cooling off in the water, albeit in a more stagnant pool;

Alligator

The weather was rather hot, so the big cats (lion, cheetah, tiger) mostly stayed out of the sun (and therefore impossible to photograph). I did manage to get a few shots of the leopard and ocelot, however;

Leopard

Ocelot

The animals in the African plains enclosures were a bit more active, however, including the Reticulated Giraffes and Grey’s Zebra (previously I had only seen Grevy’s Zebras);

Giraffe

Zebra

While not as exotic, the raccoons and swift fox the zoo kept provided me with some decent shots as well;

Raccoon

Swift Fox

Before leaving, we also stopped into the “World of Birds,” where I encountered this strange species with yellow waddles (and showed no fear or concern that I was photographing it from so close a range);

Bird

Bird

Not long afterwards, we ate our dinner and headed for home, overall being a good day in Cape May. I also wanted to include this picture of a deer I got a few weeks ago in Pennington, NJ, where I was petsitting;

Deer





Photo of the Day: Chilled Cheetah

12 07 2007

Cheetah

This is one of a male coalition of three cheetahs at the Philadelphia Zoo, this photo being taken in the early afternoon on a cold January day. A female cheetah is going to be introduced to the zoo soon, so there may very well be baby cheetahs in Philadelphia soon.





Are you smarter than a Hyena?

3 07 2007

Spotted Hyena (Crocuta crocuta), the “bad guys” of the African plains. My wife is repulsed by them, but I find something oddly intriguing about these predators; any social carnivore in which the female has a functioning pseudo-phallus nearly indistinguishable from the male’s is bound to stand out.

Spotted Hyena Skeleton

Spotted Hyena are extremely effective, social predators, being much more effective hunters than many people think. The classic African battleground, at least in the mind of the public, features a pride of lions valiantly defending a kill from a pack of dastardly hyenas, laughing and yipping in a way that can only be described as disturbing. Just as likely as not, however, the favored lions are trying to steal prey killed by hyenas, both groups of carnivores vying for the top position in their habitats (cheetahs, wild dogs, leopards, and other smaller predators typically give up their kills to the more formidable lions and hyenas). The social structure and coordination utilized by hyenas requires a fair amount of intelligence, however, and I have previously hypothesized that binocular vision (accompanied by the existence of lips and eventually shortening of the face) had some role to play in the evolution of intelligence, allowing carnivores a greater ability to form complex social structures based upon facial/body cues (binocular vision is the key step to the beginnings of having a “face”) than herbivores with eyes on each side of their head. Likewise, a new study in the Journal of Mammalogy by Holekamp, et al. looks at how the intelligence of Spotted Hyena may be convergent with that of some primates with a similar social structure.

Intelligence is a costly thing to have, especially metabolically speaking; it takes a lot of energy to run what’s inside your noggin, so whatever selective forces produced our big brains must have been of considerable advantage (or allowed to keep acting as we were better able to literally feed our brains). The authors of the paper outline two hypotheses about the circumstances that favored the evolution of great intellectual capacity;

The 1st hypothesis suggests that these traits were favored by selective forces in the physical environment, such as the need to learn and recall when fruit might become available on trees that fruit sporadically, how to use tools to extract difficult foods, or how to navigate visually through a 3-dimensional arboreal world (e.g., Milton 1981; Povinelli and Cant 1995). The 2nd hypothesis, known broadly as the ‘‘social complexity’’ hypothesis, suggests instead that the selective force favoring big brains and advanced cognition in primates was the need to anticipate, appropriately respond to, and manipulate the social behavior of conspecifics (reviewed in Byrne and Whiten 1988).

I look at this problem not from the angle of one over the other, but rather “Which came first and which had the largest impact at any given period?” but the authors state the social complexity hypothesis seems to have more evidence to support it, although studies in non-primate animals are lacking. If the social complexity hypothesis is correct, however, we should see evidence of convergence among other groups of animals similar in social structure to primate groups, and this makes the spotted hyena an ideal subject to test this hypothesis. Indeed, the social structure of the hyenas seem to have parallels with the primate subfamily Cercopithecinae (“baboons, macaques, vervets, guenons, talapoins, patas monkeys, and mangabeys”), the carnivores providing a good “independent test” given that the last common ancestor they shared with primates existed during the late Mesozoic.

Like primates, spotted hyenas do not produce large amounts of offspring per pregnancy (usually 1 to 2 cubs are born at a time) and the young a fed milk for an extremely long time, up to 24 months (the copious amounts of bone hyenas ingest keeps the milk flowing for this extended period). In fact, the period during which hyenas are nursed surpasses that of the primate analogs considered in the paper, but the hyenas do become reproductively ready in about the same time-frame as the primates (male hyenas are ready essentially when weaned {although this doesn’t mean they successfully mate at this time}, females begin mating between 3 and 4 years). Indeed, the authors of the study have produced an entire table for comparison between hyenas and the primates, and the lack of substantial differences are surprising. Let’s take baboons as our prime analog for the hyenas; both live in large groups of animals related through mothers that stay in the group, dominance being determined via a hierarchy of display and combat, cooperative resource sharing, individuals maintaining bonds with kin, individuals preferring higher-ranking members for same-sex social partners, etc. Indeed, the primary differences seem to be that hyena clans are female-dominated and that hyenas engage in cooperative hunting, the overall social structure of the distantly-related mammals being surprisingly alike.

While we do benefit from the overall comparison of behaviors shared by certain primates and hyenas, the ability to recognize 3rd-party relationships is an important sign of the intelligence an animal may possess. It’s easy to remember who is higher or lower than yourself in a social hierarchy, but to be able to recognize the status of, for example, two fighting hyenas and side with the higher ranking one to gain favor can be quite useful. The authors describe the test of 3rd-party relationships among hyenas in this way;

Thus, a hyena considering an attack might benefit, for example, when attempting to displace a larger subordinate animal from food, by delaying its attack until the arrival of a potential ally who is higher ranking than the target animal. If a hyena increases its rate of aggression only after a hyena that is higher ranking than itself arrives on the scene, then the animal might be following a simple rule of thumb, such as ‘‘Only attack a larger subordinate when another individual is present who is higher ranking than yourself.’’ Use of this sort of simple mental algorithm would not require that hyenas be able to recognize 3rd-party relationships among their group-mates. However, if a hyena’s attack rate also increases after the arrival of an individual who is dominant to the victim but subordinate to the attacker, then the attacking hyena must recognize the relative ranks of the other 2 individuals. In the latter case, the hyena would be demonstrating that it can indeed recognize tertiary relationships.

In considering dominance it should be noted that mere size does not mean everything, especially for young hyenas. Young hyenas are born into the rank just below their mothers, and so it was quite easy for a larger hyena to be subordinate to others unless it is able to establish itself through a fight. Being able to call utilize a cohort to prevent a larger animal from winning in a battle would be a good way to preserve the hierarchy in spite of size difference. Even if two hyenas are fighting and a more dominant individual arrives on the scene, it will side with the more dominant of the two individuals in the dispute, and so it is a very bad day for a hyena when a subordinate attacks a more dominant individual without any support, nor is it good for the relatives of the losers. In addition to the imposed dominance hierarchy, hyenas also recognize kin relationships, and after fights whichever hyena was the aggressor is more likely to act aggressive to the kin of the victim, even taking out aggression on the kin of their opponent more than on unrelated lower-ranking members (which Sapolsky described many times among baboons in A Primate’s Memoir). Still, there’s much we don’t know about hyena interactions, and more work needs to be done before we can more completely compare it to the behavior of baboons.

The spotted hyena is just one of several related animals belonging to the Family Hyaenidae, and all of its relatives are less gregarious, even to the point of not living in groups at all. The authors call for further research into cognition and intelligence with these animals as well, being that if the close relatives of the spotted hyena lack some of its cognitive abilities we can better discern how social complexity has influenced the evolution of intelligence. Just as well, study of the brains of hyenas is desperately needed; not only do we need to observe social structure, but to see if these animals have “social brains” as well. If the social complexity hypothesis is correct, we would expect the frontal cortex of the spotted hyena to be more developed than that of its less-gregarious relatives, and the same type of study could be carried out with lions in relation to other big cats. Speaking of lions, I also have to wonder how lions and spotted hyenas may have driven each other into forming prides or clans; while it’s easier to gain food as a group, it would also be easier to protect or steal food in a group rather than acting as an individual. Unfortunately the behaviors of these animals is long gone, but I can’t say that I don’t wonder about it.

But wait, there’s more! In looking for other papers to tie into this discussion I happened across Samuel Gosling’s 1998 paper “Personality Dimensions in Spotted Hyenas (Crocuta crocuta),” describing the various behavioral traits of 34 hyenas based upon “Assertiveness, Excitability, Human-Directed Agreeableness, Sociability, and Curiosity.” This sounds a little anthropomorphic at first, but animals are not all merely carbon-copies of each other, behaving in a certain fashion because they are merely programmed to do it. No, anyone who is familiar with any group of animals (especially social mammals) for any length of time can distinguish distinct personalities in the group, and the existence of varied personalities amongst hyenas speaks to their intellectual capacity as well. Indeed, what Gosling found was that dominance hierarchy alone could not explain all the behaviors of the captive hyenas studied, the only strong correlation made being females are more “assertive” than males (which is to be expected in a female-dominated social species). “Agreeableness” to keepers may also have been influenced by dominance, the keepers being viewed as being more dominant by some hyenas, but this relationship between humans and hyenas likely goes out the window when dealing with wild populations.

Spotted hyena are absolutely amazing social carnivores, one of the animals most indicative of Africa. They are easy to malign, but can be difficult to understand, but gaining such understanding may help us answer some important questions about how we came to be as we are. While I’m sure it will be a bit nerve-racking, I do look forward to my first night in Africa someday, hearing the “whoops” of the hyena across savanna at night.





Just what is a Nimravid, anyway?

28 06 2007

Holophoneus Skull
Hoplophoneus sp. via Wikipedia

The saber-toothed cat is one of the most famous of prehistoric icons, but perhaps one of the most neglected when it comes to public understanding. While we know dinosaurs by their genus names (names like Tyrannosaurus, Apatosaurus, and Ankylosaurus are easily come to mind), few people are familiar with saber-toothed cat genera like Smilodon, Metailurus, Dinofelis, or Xenosmilus (and there are many more). What’s even more confusing is that what we often call a saber-toothed cat is not really a cat at all, but a related carnivore called a nimravid that was molded by a striking trend in parallel evolution.

Up until a few months ago, I have never even heard of the term “nimravid”, and I was quite surprised to find out that Barbourofelis and Hoplophoneus, two creatures I had always assumed were just another kind of saber-toothed cat, could not be called true cats at all. Skulls of these two genera (or manufactured facsimiles) usually sit in the same displays as those of Smilodon and other more-familiar saber-tooths, and I never thought twice to look for differences. How careless I was not to pay attention, and how careless of museums to keep lumping the remains of these separate lineages together with minimal comment.

Part of the problem with tracing the evolutionary history of mammalian carnivores is that they have generated an amazing amount of different forms; there is much diversity and plenty of branches, so every new fossil certainly can shake the tree. To keep things simple, however, all living carnivores evolved from a line of primitive carnivorous mammals called Miacids, with the Order Carnivora first becoming recognizable sometime during the Eocene (approx. 56-34 million years ago), the groups giving rise to modern dogs (Family Canidae) and cats (Family Felidae) diverging about 43 million years ago. Not all the groups that arose from the first true carnivores left living descendants, however, and such is the case with the nimravids.

Hoplophoneus
Hoplophoneus mentalis via Wikipedia

So, what makes a nimravid a nimravid? They look awfully like cats, so why aren’t they lumped into the Family Felidae? What makes such distinctions so difficult is that those looking upon the skull of Smilodon and Eusmilus would have to be relatively well-versed in scientific jargon and anatomy in order to point out the most important differences. While some nimravids (like Eusmilus) had large canines, their teeth alone are not diagnostic, and the original factors used by E.D. Cope that differentiated these animals from “true” cats were the “alisphenoid canal, postglenoid foramen, carotid, posterior lacerate, and condyloid foramina, postparietal foramina” in the skull (Hunt, 1987). The various canals and foramina listed dictate the paths of various nerves and blood vessels in the skull, and the arrangement in nimravid skulls seem to be more primitive compared with true felids. Likewise, nimravids lack a two-chambered auditory bulla, which is a rounded bit of bone associated with the ear which true cats have (here’s a diagram of a dog skull pointing out the location of the bulla).

There are a few more obvious giveaways when dealing with some nimravids, however. Nimravids equipped with long canines often have more cone-shaped canines than saber-toothed cat canines (which are flatter in cross-section), and many have bony “sheaths” extending from the lower jaw into which the massive teeth fit. Perhaps the most famous example of this kind of arrangement is the genus Barbourofelis, an animal that has actually been assigned to its own family as it is likely more closely related to true cats than nimravids (Barbourofelis was previously classified as a nimravid). Because of this (and the fact that another cat-like offshoot, the marsupial Thylacosmilus) the tooth-sheath shouldn’t be considered diagnostic of nimravids only, but it does give you a substantial clue that you’re probably not dealing with an actual saber-toothed felid.

Saber-tooths
Skulls (mandibles not pictured) of 4 “saber-toothed” mammals from “The Function of Saber-Like Canines in Carnivorous Mammals” by G.G. Simpson, American Museum Novitiates, August 4, 1941. Pictured are A) Machairodus (felid), B) Hoplophoneus (nimravid), C) Smilodon (felid), and D) Thylacosmilus (marsupial).

You can see how complicated things can get; three different groups of animals arriving on the same body form from the same group of ancestors within a short amount of time. Indeed, saber-teeth seem to be a very common consequence for carnivores in this particular group, and oddly enough some living herbivores like the Musk Deer have impressive fangs as well. I’m not well-versed in evo-devo, but perhaps studying why musk deer develop such impressive teeth might give us some clues as to how it happened in these extinct cats, despite different ancestry. I should also perhaps mention that I’m curious about any sexual dimorphism between male and female saber-bearers; could sexual selection had a role in the extension of these massive canines? I don’t think it’s unreasonable to think so, especially if (as we’ll discuss) they were so long that they seemed to make these carnivores even more specialized in hunting, feeding, and social behavior than living carnivores.

Given the prevalence of massive canines amongst extinct felids and other groups, it’s a wonder why there are none living today (it should be noted, however, the Clouded Leopards have very long and impressive canines, even though they don’t peek out of their mouths when closed). It should also be noted that I have essentially left out a number of other, more distantly related saber-toothed carnivorous mammals called creodonts, which held saber-toothed hyenas like Hyaenodon in its ranks. For a time, it must have seemed like everyone and their mother had impressive fangs, and I can only wonder as to how these impressive structures became so-widespread.

It is not enough to merely say that nimravids are different, however; if they are not true saber-toothed felids, how closely are the groups related? Initially, some scientists thought that nimravids were ancestral to true cats based upon their more-primitive skull structure. As more fossils came out of the ground, the hypothesis that nimravids are closely related to true cats without being ancestral to them became favored, but this was overturned by the idea that nimravids and true cats are not very closely related, the nimravids diverging from the line that led to cats much earlier. This third view seems to make the most sense given the current fossil evidence, but I have to wonder how the reassignment of Barbourofelis will affect things, especially if it’s considered to be closer to felids than nimravids.

Here is a visual representation of the three hypotheses (which could be entitled “I can has MS Paint?”), after Hunt’s diagram in his 1987 paper;

Nimravid/Felid evolution

I included the “ancestral line” label in order to enforce the changing ideas about how evolution works, as well. In the first example the animals just kept evolving in the same line (they were the same genetic line, just with different species names as we came across them in the fossil record), but the third diagram shows that just because a new branch emerges does not mean that the ancestral line stops immediately. I have omitted Thylacosmilus and Barbourofelis as to keep things as simple as possible, and the fact that whatever I came up with would merely be a guess. I would also be remiss if I did not point this fact; while true saber-toothed cats do belong to the Family Felidae, they are all grouped together in the Subfamily Machairodontinae and do not have any living descendants. They diverged fairly early during felid evolution, ultimately becoming extinct, and I have hence tried to avoid the term “saber-toothed tiger” as much as possible. Because I’m trying to focus on nimravids for this entry I will keep the designation of “felids” for true saber-toothed cats, and hopefully I’ll eventually write a piece with more detail about the more well-known carnivores.

The big question involving these animals, however, is “How in the hell did they actually use those teeth?” Given that saber-toothed mammalian predators evolved three times in a geologically short time in three separate groups of predators suggests that they were useful for something, but how do you bite with teeth that extend past your lower jaw? In considering this question, it’s important to remember that when biting only the lower jaw is actually moving, so if a saber-toothed mammal wanted to impale a prey item with its long canines, it would have to throw its neck around with considerable force to achieve that end. In fact, this kind of action has already been proposed by some, the dynamics of felid saber-tooth skulls making it difficult to conceive how such huge canines could be used to effectively bite prey.

Part of the problem with having saber-teeth is that you need to open your jaw exceedingly wide in order to get food in your mouth. The oft-cited measurement for the gape of the felid Smilodon is 120 degrees (no source I’ve seen references where this measurement came from), and even if this is wrong we know that in order to get food into their mouths, many of the hyper-saber-toothed mammals would need to open their jaws to a 90 degree angle or more, otherwise they would not be able to get food in their mouths. What this means, as far as muscle strength is concerned, is that the muscles would not be as strong as in other cats, getting the mouth open being more important to a strong bite, so saber-toothed mammals would not have the crushing power of modern tigers or lions. Likewise, owning saber-teeth can make hunting difficult; if you stick your teeth into a live animal and it struggles, you could very well lose a tooth. Likewise the teeth would be more fragile, so putting extreme stresses on them (like crushing bone) would largely be out of the question too; it would be more effective and safe to attack soft parts of an animal than to try for the take-down neck-bites that modern cats employ.

We should be careful in our assumptions, however; we’re dealing with extinct animals, and their method of capturing/subduing prey may have differed significantly from any living carnivore. While I just mentioned that saber-toothed mammals likely had weak jaws, a 2005 study suggests that they had jaws as strong or stronger than living big cats, with different killing strategies depending on the overall durability/robustness of the saber-teeth. Likewise, an earlier study (1996) based upon tooth wear in Smilodon was unable to match wear indicative of bone crushing/chewing/abrasion with living hyenas, canids, and cats, suggesting that Smilodon may have avoided contact with bone as much as possible. Indeed, even though all these animals had impressive canines, not all their canines were equal, and some would be better suited to dealing with stresses involved with prey capture than others. Still, I would regard many of these teeth as delicate, and I can only imagine the pain these mammals must have endured when one of them broke.

Other hypotheses about how these animals employed their teeth involves the white shark-like tactic of disemboweling the softer underbelly of prey, then waiting for the eviscerated creature to die. This would be a rather risky move, the predator essentially sticking its head right between both sets of sharp hooves (assuming the prey was an ungulate). What seems more reasonable would be a strategy based upon cooperation, much like modern lions taking down huge water buffalo. If the group could bring down the prey with their claws, one animal could deliver the killing bite to the neck, minimizing the amount of potential harm to itself. This hypothesis, however, requires the study of behavior that we are no longer privy to, and it would be unreasonable to infer such a pattern on all saber-toothed mammals as the rule.

In his own paper studying the various methods of attack saber-toothed mammals could have used, G.G. Simpson concluded that they were best adapted for stabbing, not as much for slicing (although he conceded that they likely did this as well), the dentition of these animals showing their predatory habits (it had been hypothesized earlier that these animals may have been scavengers). Simpson’s study is interesting, but prey is generally not taken into account; only the effectiveness of different strategies for ripping up the assumed prey. While it certainly serves as a good reference point from a mechanical point of view, the skulls of the animals are considered out of context, and so the major mysteries of these animals remain unsolved.

Ultimately, all the known saber-toothed predators died out, regardless of their affinities. One of the most popular views (which I am surprised to still hear) is that the teeth of these animals simply became so huge that they could not properly open and close their mouths, driving the species to extinction. If there are urban legends in paleontology, surely this is one of the most annoying and persistent. G.G. Simpson refutes this idea in his popular work The Meaning of Evolution, published more than 30 years before I had heard it from various documentaries claiming scientific accuracy;

The sabertooth is one of the most famous of animals just because it is often innocently supposed to be an indisputable example of an inadaptive trend. In fields far remote from paleontology the poor sabertooth has some to figure as a horrible example, a pathetic case history of evolution gone wrong. Its supposed evidence is thus characteristically summarized in a book on (human) personality: “The long canine tooth of the saber-toothed tiger grew more and more into an impossible occlusion. Finally, it was so long that the tiger could not bite effectively, and the animal became extinct.” Now, like so many things that everyone seems to know, this is not true… Throughout their history the size of sabertooth canines varied considerably from one group to another but varied about a fairly constant average size, which is exactly what would be expected if the size were adaptive at all times and there were no secular trend in adaptive advantage but only local and temporary differences in its details. The biting mechanism in the last sabertooths was still perfectly effective, no less and probably no more so than in the Oligocene. To characterize a finally ineffective a mechanism that persisted without essential change in a group abundant and obviously highly successful for some 40,000,000 years seems quaintly illogical! In short, the “inadaptive trend” of the sabertooth is a mere fairy tale, or more fairly, it was an error based on too facile conclusion from imperfect information and it has since been perpetuated as a scientific legend.

Why saber-teeth seemed to be so trendy among predatory mammals, only to disappear entirely, I have no idea. Obviously they must have been good for something, some common developmental, ecological, or other trend driving canines to be longer, only to (perhaps) cause the animals to be so specialized that they could no longer compete with other carnivores who did not have to be so concerned about their teeth. At the very least, however, I hope this post have served to bring to attention a group generally overlooked, often mistaken for their cousins, when they have a rich evolutionary history of their own.

References;

Hunt, R.M. 1987. “Evolution of the Aeluroid Camivora:Significance of Auditory Structure in the Nimravid Cat Dinictis“, American Museum Novitiates, Number 2886, pp. 1-74

Simpson, G.G. 1941. “The Function of Saber-Like Canines in Carnivorous Mammals“, American Museum Novitiates, Number 1130

Further Reading;

The Big Cats and their Fossil Relatives by Turner and Anton

The Velvet Claw by MacDonald

Evolving Eden by Turner and Anton

Fatalis by Rovin (fiction)

Wild Cats of the World by Sunquist





A Real-Life “Big, Bad Wolf”

22 06 2007

Mexican Wolf
A Mexican Wolf (Canis lupus baileyi), the most genetically-distinct subspecies of Grey Wolf (Canis lupus) at the National Zoo in Washington, D.C.

One of the most famous stories in the history of paleontology is of how William Buckland, the noted 19th century geologist, determined that a pack of hyenas once inhabited Kirkdale Cave in Yorkshire, England by observing the markings living hyenas made on bones at the zoo. While the science of taphonomy would not fully emerge until the next century, it became clear that fossil bones could tell us about scavengers and predators as well as the preserved prey. It’s no surprise that hyenas especially would “make their mark” on so many bones, the extant Spotted Hyena (Crocuta crocuta being well known for its jaw strength and ability to crack bone (which provides mothers with extra calcium for milk, and these hyenas nurse their young for a relatively long period of time as pups are not weaned until they are a year older or more). Now, a new study of various wolf remains reveals a Pleistocene predator distinct from the Grey Wolves in Yellowstone or anywhere else in North America. The abstract of the new Current Biology paper “Megafaunal Extinctions and the Disappearance of a Specialized Wolf Ecomorph” by Leonard, et al. states;

The gray wolf (Canis lupus) is one of the few large predators to survive the Late Pleistocene megafaunal extinctions. Nevertheless, wolves disappeared from northern North America in the Late Pleistocene, suggesting they were affected by factors that eliminated other species. Using skeletal material collected from Pleistocene permafrost deposits of eastern Beringia, we present a comprehensive analysis of an extinct vertebrate by exploring genetic (mtDNA), morphologic, and isotopic (d 13C, d 15N) data to reveal the evolutionary relationships, as well as diet and feeding behavior, of ancient wolves. Remarkably, the Late Pleistocene wolves are genetically unique and morphologically distinct. None of the 16 mtDNA haplotypes recovered from a sample of 20 Pleistocene eastern-Beringian wolves was shared with any modern wolf, and instead they appear most closely related to Late Pleistocene wolves of Eurasia. Moreover, skull
shape, tooth wear, and isotopic data suggest that eastern-Beringian wolves were specialized hunters and scavengers of extinct megafauna. Thus, a previously unrecognized, uniquely adapted, and genetically distinct wolf ecomorph suffered extinction in the Late Pleistocene, along with other megafauna. Consequently, the survival of the species in North America depended on the presence of more generalized forms elsewhere.

Unfortunately there are no photographs or illustrations of the skulls studied to reach these conclusions, but as with other mammals the condition and placement of the teeth is absolutely key. This extinct group of wolves had a much higher amount of tooth wear and fracture than modern wolves (or even other groups of extinct carnivores like Dire Wolves and Saber-Toothed Cats), as well as having a skull shape that would have granted them greater bite forces. These wolves also seem to have had a relatively deep (I assume we’re talking from top to bottom) jaws, characteristic of bone-crackers like hyenas and living wolves that take down large prey. This wolf was not particularly larger than wolves currently living in Alaska or fossil wolves from the La Brea Tar Pits, but the construction of its skull and tooth wear make it apparent that it certainly was an effective predator and scavenger.

The evolution of these wolves is also covered in the paper, and it seems that the bone-crushing wolves and extant wolves share a common ancestor that came from Europe or elsewhere in the Old World, the genetic tests showing that the “new” wolves were not the ancestors of modern Grey Wolves. Instead, it seems that the more robust wolves to the north were middle-weights as far as carnivore ecology (Dire Wolves being larger, Coyotes being smaller), and when Dire Wolves became extinct the Grey Wolves began to become adapted to taking larger prey and cracking bones. The authors of the paper suggest that being an overspecialized “hypercarnivore” may have ultimately done the wolf in, its more generalized southern cousins better able to adapt to changing conditions at the end of the Pleistocene. I’m not particularly sure about this argument, but I’m not expert enough to prove it incorrect either.

In any event, I hope more researchers dive into the mountains of fossil remains languishing in museums all over the world; I almost have to wonder if there are just as many species waiting in dusty cabinets as there are still waiting in the rock.





Learning to fear predators, OR Ecologists have more fun

22 06 2007

One of the most well-known (albeit misunderstood) tales of extinction is that of the dodo; while the birds were capable of defending themselves if necessary, they generally did not fear sailors that came onto the islands. The dodos were beset by an invasion of men, pigs, rats, and other creatures they had no experience with, and the ecological degradation as well as their inability to consider man a predator led to the ultimate demise of the species. I can only wonder if the dodo would have persisted if their pressures upon it were not so acute; would it have learned to be wary of humans? That is a question that cannot be answered, but a new study by Dr. Joel Berger of the WCS has uncovered some surprising insights into predator-prey interactions, revealed in the new paper “Carnivore Repatriation and Holarctic Prey: Narrowing the Deficit in Ecological Effectiveness” in the journal Conservation Biology (and I just canceled my subscription due to lack of service too. Damn!)

Keystone predators have been nearly eradicated in their natural ranges all over the world, wolves, tigers, and brown bears being some of the most notable carnivores. In their absence, new generations of ungulates like moose and deer have never learned what a wolf howl or tiger growl sounds like, and so they have little response to the sounds and smells of predators. Using recordings (and perhaps even urine-soaked snowballs), Berger has found that prey animals typically do not react quickly to various stimulus that would indicate a predator they have no experience with. There have been efforts to reintroduce predators, however, and wolves were successfully brought back to Yellowstone in 1995. When Berger found was that the Bison in Yellowstone had learned to recognize wolf howls, responding even more strongly than bison in other areas that have had constant contact with wolves over many generations, showing that prey animals can indeed learn to fear predators again.

Also of importance is the area in which the prey is located when confronted with signs of a predator; snow depth and distance from cover may make a difference as to how prey reacts. Unfortunately I don’t have access to the whole article, but it sounds absolutely amazing. I can only imagine what it must have been like to undertake such a study; visiting locations all over the world in order to quiet fears that predators will decimate prey populations if introduced. So, I can has grant to continue research?

Paper abstract;

The continuing global decline of large carnivores has catalyzed great interest in reintroduction to restore populations and to reestablish ecologically functional relationships. I used variation in the distribution of four Holarctic prey species and their behavior as proxies to investigate the pace and intensity by which responses are lost or reinvigorated by carnivore repatriation. By simulating the presence of wolves (Canis lupus), tigers (Panthera tigris), and brown bears (Ursus arctos) at 19 transcontinental sites, I assayed three metrics of prey performance in areas with no large terrestrial carnivores (the polar islands of Greenland and Svalbard), extant native carnivores (Eastern Siberian Shield, boreal Canada, and Alaska); and repatriated carnivores (the Yellowstone region and Rocky Mountains). The loss and reestablishment of large carnivores changed the ecological effectiveness of systems by (1) dampening immediate group benefits, diminishing awareness, and diminishing flight reaction in caribou (Rangifer tarandus) where predation was eliminated and (2) reinstituting sensitivity to carnivores by elk (Cervus elaphus) and moose (Alces alces) in the Yellowstone region to levels observed in Asian elk when sympatric with Siberian tigers and wolves or in Alaskan moose sympatric with wolves. Behavioral compensation to reintroduced carnivores occurred within a single generation, but only the vigilance reaction of bison (Bison bison) in Yellowstone exceeded that of their wolf-exposed conspecifics from boreal Canada. Beyond these overt responses by prey, snow depth and distance to suitably vegetated habitat was related to heightened vigilance in moose and elk, respectively, but only at sites with carnivores. These findings are insufficient to determine whether similar patterns might apply to other species or in areas with alien predators, and they suggest that the presumed excessive vulnerability of naïve prey to repatriated carnivores may be ill-founded. Although behavior offers a proxy to evaluate ecological effectiveness, a continuing challenge will be to understand how naïve prey respond to novel or introduced predators.





Is there a civet in your perfume?

3 06 2007

One of the most curious aspects of dating and relationships in technologically advanced countries is the need for people to cover up their natural scent with lots of different products. For my own part, my current shampoo, conditioner, body soap, deodorant, and cologne are all different, and I douse myself with foreign scents to make sure that I do not offend the olfactory sensibilities of others. But where do such scents come from? There are plenty of synthetic chemicals that mimic naturally (or unnaturally) occurring scents, but, interestingly enough, some fragrances still require animal sources. As Terry Pratchett wrote in The Unadulterated Cat (which ironically sits next to a basket of the products I mentioned above in the bathroom);

Civet

An 1894 Richard Lydekker painting of an African Civet

The civet cat has been a nervous animal ever since it discovered that you can, er, derive civetone* from it and use it in scent. Exactly how this is done I don’t know and do not wish to research. It’s probably dreadful. Oh, all right, I’ll have a look.

It is.+

*A 17-member ring-ketone, according to my dictionary, as opposed to the mere 15-membered muscone from the musk deer. Does the civet feel any better for knowing this? Probably not.

+Who invents these scents, anyway? There’s a guy walking along the beach, hey, here’s some whale vomit, I bet we can make scent out of this. Exactly how likely do you think this is?

Indeed, the civet’s (specifically the African Civet, Civetticus civetta) scent is also useful to those wishing to track big cats, a researcher in a recent issue of Natural History relating that central american jaguars (Panthera onca) are especially drawn to the civetone in Calvin Klein’s “Obsession.” Good to know if you’re in search of big cats, but it still leaves the question of what civetone actually is and why it is important. For that, I turn to Richard Despard Estes Behavior Guide to African Mammals, in which he describes the olfactory communication of the animals;

Olfactory Communication: scent-marking with dung, urine, perineal gland.
Perineal-gland marks appear to be concentrated on trees fronting roads and pathways, especially trees that produce fruit eaten by civets. A passing civet pauses every 85m or so to press the everted gland against a trunk. The secretion is a thick, yellowish grease that hardens and turns dark brown and more visible with age, while the powerful and disagreeable scent remains detectable for at least 4 months. The musk scraped periodically from the perineal gland of captive African civets is refined into civetone, which “exalts” the fragrances of expensive perfumes.

Why not just cut out the middle-man and press a civet’s butt to your arms, neck, or chest? Such is what a cartoon (and rather low-quality article) from the Softpedia article “Get the best perfume from the cat’s a**” portrays. This is not entirely accurate as the civet’s secretions must be combined with alcohol and other chemicals to bring out its “pleasant musky odor,” but this does not change the fact that for centuries fragrance makers have relied on greasy secretion near a mammals anus to produce more pleasant personal scents.

Fortunately, synthetic civetone has been produced, but many “high-quality” perfume manufacturers still prefer scraping a civet’s musk glad the old fashioned way. From Yilma D. Abebe’s “Sustainable utilization of the African Civet (Civetticus civetta) in Ethiopia” (which is also found complete here);

Despite civet musk being produced artificially in the late 1940’s, high quality perfume producers still prefer the use of civetone (Anonis 1997). Demands for a synthetic alternative have been growing in recent years however with the British Fragrance Association (BFA) and the International Fragrance Association (IFRA) of the opinion that perfume industries are more likely to use artificial musk (Pugh 1998).

Indeed, the harvest of “natural civetone” continues, (despite some web sites suggesting that it has stopped with the invention of synthetic civetone) and while the African Civet is not threatened it does not change the fact that cruel practices have been recorded among civet farmers and wild civets are continually caught to replace those that die of stress in captivity (I’ll leave you to imagine why they’re so stressed).

The author also notes that local superstitions and husbandry practices make the trade very hard to regulate and control, and the process is considered unsustainable (although unlikely to stop because of economic gain associated with civet farms). Also of interest is the assertion that predominantly Muslim farmers in Ethiopia harvest civetone from civets. The author writes;

In Ethiopia, only Muslim communities are practice civiculture. According to oral history the legendary leader Nessiru Allah, who lived in Limu, Keffa, suffered from an eye affliction that was cured by an application of civet musk. Once cured, Nessiru Allah ordered followers of Islam to farm African civets (Mesfin 1995).

So what are we to do? Personally, I would check your own perfumes to see if “civetone” is listed in the ingredients, and even contact various perfume companies to see if they’re using civetone derived directly from civets and to ask for a ban on using the harvested secretions from the carnivores. Even if large companies switched over to artifical civetone, however, the practice would likely survive to some degree in Ethiopia and would be resistant to reform, so local and government workers would have to work with the farmers to ensure humane practices (i.e. scraping civet musk off bars or posts they deposit it on rather than sticking a spoon into the animal’s gland) and open up other economic opportunities so that the farmers are not relying on civets for income (even in the IUCN report mentioned above, civetone seems to be bringing in less and less money to Ethiopia). Such is the problem with humane practices and conservation, however; merely establishing the science aspect will not convince the farmer who needs income from his practices, and care for both the animals and people is needed if a positive change is going to be made.

End Note: Civets aren’t the only animals to be farmed for particular scents or secretions; bears and musk deer (also important to the fragrance industry) suffer similar consequences as well, and both will require seperate posts to do their stories justice.

End Note 2: I’ve corrected some of the mistakes I made in the initial post. I started getting a pretty bad migraine in the middle of writing this so I didn’t entirely pay attention to what I was doing. I’ll have some more posts up when I recuperate.





Had enough yet?

2 06 2007

Just in case you haven’t had enough of my photography today, Jeremy Bruno of The Voltage Gate has graciously put up some of my Red Panda photos from the Bronx, Philadelphia, and National Zoos. Some you’ve seen here, some you have not, so go check it out (and don’t forget to check out his posts on the cute little critters, too!)





More Zoo Photos; Bears, Peafowl, & Otters

11 05 2007

Last weekend some friends and I visited the Bronx Zoo (thanks Tim!) and I snagged a few shots; nothing incredibly dazzling or new, but I thought a few people might enjoy them. First up, a tiger I had not previously seen before, although I’m not sure whether this is one recently brought to the zoo or one that I just never ran into previously;

New Tiger

Tiger Drink

As always, the black leopards of Jungle World were fast asleep, although I did manage to get a halfway decent photo this time (although I’d need to remove the crease from the glass in the background);

Black Leopard

I did get to see the otters, however, which are not typically out when I come to visit;

Otter

The second time I ever visited the zoo I came across an amazing sight; two Blesbok fighting during the beginnings of a thunderstorm. Unfortunately I hadn’t seen them since then, but I did manage to get this picture during my last visit;

Blesbok

The giraffes were out as well, although none came close enough to get a decent shot;

Giraffe

And of course, I couldn’t not drop by to see the cheetahs;

Cheetah

The grizzly bears were still playing as well, this time sloshing about in their little pool;

Bears playing

My favorite shot, however, is of one of the animals that is so ever-present in the zoo I normally don’t take the time to photograph them; a male peacock. This one was having a rest under a bush and allowed me to get close enough to get a ground-level shot;

Peacock

So there you have it; like I said, nothing especially spectacular but a few good ones in the mix. I still love visiting the zoo, but when there’s hundreds of strollers being pushed about (and of course, half the children want to walk and not be in their strollers) it’s hard to have a good time. The zoo is free on Wednesdays, but unfortunately I must work and have to fight the crowds on the weekends. As cold as it was, I almost preferred visiting when it was 26 degrees in the middle of February; then it was just me and the animals and I could take as much time as I wanted. As a whole I don’t like zoos and their focus on money rather than conservation, but I am glad that I live close enough to one of the exceptions that I can visit almost anytime.





Marine mammals take another hit

20 04 2007

When marine fish stocks decline, pinnipeds (seals and sea lions) often take the blame. Seal hunters in Canada after (wrongly) accuse seals of eating all the cod and in the Pacific northwest of the United States it appears that sea lions are being blamed for depleting salmon stocks. I first heard about this issue in a book I randomly picked up in the Baltimore, MD Barnes & Noble a few years ago, and what scientists found was that the sea lions were not eating any significant amount of salmon, at least until a “fish ladder” was created to help the fish get upstream and they became easy prey.

Years later, the debate is still raging and now a sea lion in the Columbia river has been shot twice for stealing a fish off someone’s line (it appears from the article that the fisherman didn’t do the shooting, but it was another person in the area). It seems like the sea lion is alive for the moment, but this could very soon change as the bullets could cause deadly infection. What has yet to be proven, just like the passage in the book (I wish I could remember it’s name), is that the sea lions are actually a major factor in the declining salmon fishery, and I suspect that they are once again being used as a scapegoat for poor management and biological degradation. In all this talk not once have I seen the findings of an outside scientist (i.e. not affiliated with the government or National Marine Fisheries Service) as to what these animals are eating, and if it’s salmon, how much of their diet is composed of salmon. How can we make management choices, especially ones advocating lethal force on a species previously protected under the Marine Mammal Protection Act, without any serious study of what’s happening?

Others have noticed this issue as well.

“It won’t save declining salmon runs in the Columbia River, because the sea lions aren’t the problem.” said Sharon Young, national marine issues field director for [the Humane Society of the United States]. “It seems that it is easier to scapegoat the sea lions than to try to address these other more politically charged and complex issues.”

Recently, Japanese whalers have blamed Humpback Whales for declining fish stocks, but of course we already know their motives behind this statement; Humpbacks are next on the list to be hunted, which will likely cause greater outcry being they are one of the most powerful symbols of the ocean. Luckily, however, the case for further whaling is looking worse and worse and I hope it is entirely shut down soon.

In any event, I don’t believe marine mammals are having big impacts on fisheries like some claim, and in fact they actually help fisheries by eating competing fish and other predatory fish (especially in the case of seals and sea lions) so eliminating them would be a HUGE mistake. While I hope the issues in Oregon are resolved soon, somehow I get the feeling that as long as we have declining fish stocks, marine mammals are going to get the blame instead of mismanagement by humans.