Articles on evolution

1 Comment

Evolution: How the rhino got his woolly | The Economist.

Fossil of Ancient Hairy Creature Reveals Clues About Mammal Ancestors – Yahoo! News.

Tiny Ancestor of Lions, Tigers & Bears Discovered (Oh My!) – Yahoo News.


The Butcher: Predatory behaviors of a songbird


Songbirds have many predators such as cats, hawks, and falcons. However few people know there is actually a songbird that preys on other songbirds! I am referring to the Loggerhead Shrike, Lanius ludovicianus, which feeds on insects, lizards, amphibians, small mammals, and other songbirds.

Upon first sight one could hardly believe that these birds are vicious predators. Weighing in at only 35-50 g (1.2-1.8 oz) these grey and black birds do not appear to be that formidable. However these small songbirds have several adaptations that have allowed them to become very successful predators, even capable of taking down other songbirds.

These birds have a hooked bill, similar to that of raptors like falcons and hawks, designed to hold onto the flesh of their prey. They also have a strong notch or “tooth” with which they can sever the spine of their victims. Unlike raptors they lack strong talons to hold onto their prey though. This is not a problem for these clever little birds. To overcome this inconvenience these shrikes have found a behavioral adaptation. Instead of holding their prey down to tear chunks of flesh away they will impale their prey on something. Often this will be a sturdy thorn or a barded wire fence. Some have even been seen using Joshua trees to hold their prey.

These birds have even found a way to overcome a common problem faced by all predators, prey shortages. While the hunting is good, these birds will kill more insects, songbirds, or small mammals than they could actually eat at the time. These are then stored, impaled on a spike, to provide food in case prey becomes scarce.

This is the only species of the family Laniidae (true shrikes) that is found exclusively in North America. Like many North American birds these interesting shrikes are currently in a state of decline. However, with the exception of the sub-species on San Clemente Island in California, this species is still designated as a species of least concern by the IUCN as their total numbers are still greater than 10,000 individuals. The reasons for the decline are currently not well understood. Habitat alterations (such as the conversion of pastures to croplands and urbanization) along with the use of pesticides are thought to be key players in the downward trend. On a positive note, conservation efforts of the San Clemente sub-species have increased the numbers of this group from 14 individuals in 1990 to 46 pairs and 100 juveniles in 2009.

Loggerhead Shrike Photo


Range Map:





Photos courtesy of:





Killers of the Deep?

Leave a comment

The past few weeks  have been rather busy with both a four week business trip and the start of the new semester. This led to missing several postings and for that I apologize. Now that I am back to business I wanted to start off with a topic inspired by Discovery Channel’s Shark Week.

Sharks and humans have a long, often troubled relationship. In ancient times sharks were revered and often considered as Gods or at least to have been sent by a God for some purpose or other. Nowadays sharks are sadly seen as monsters most of the time due to their man eating reputation. But why is it that most people have this inherent fear or hatred of sharks but not of other apex predators such as lions, tigers, or bears (oh my!). Probably the reasoning is that most people live in areas where they are unlikely to see these other predators. On the other hand just about everyone loves to go to the beach or ocean, and must therefore run the risk of encountering sharks. Another possible reason is that encounters with bears and such happen on land where we feel comfortable. Sharks attack us in the water, where we are out of our element and vulnerable. They can make us feel unsafe when in the ocean and therefore society seems to have placed a special kind of hatred on them.

However there are many people trying to overcome this stigma by attempting to understand sharks and share that understanding with the world. It is in their honor, and respect for one of the greatest predators this world has ever seen, that I write this posting and try to share their knowledge.

Out of roughly 350 known species of sharks only 20 species have a history of attacking humans, with most of these attacks being perpetrated by only three species- great white, tiger, and bull sharks (Discovery). But how likely are shark attacks really? It turns out that on average there are only 70 confirmed shark attacks each year  with only around 10 of those being fatal (National). This means that more people die each year driving, giving birth, or going to hospitals. However, humans are much more dangerous to sharks. In fact National Geographic states that shark deaths at human hands range from 20-100 million animals per year and that some species have plummeted as much as 30-50% (National).

The truth is humans are not natural prey for sharks and most attacks are accidents. Those few that are fatal are likely cases of mistaken identity in which the human somehow resembled natural prey and the shark went into predatory mode. Examples of this happen when a great white mistakes a surfer paddling for a seal or a recent case was when a tiger shark reportedly mistook a swimmers camouflage patterned shorts for the pattern of a turtle shell. The bulk of shark “attacks” had been reported as test bites by juvenile sharks simply trying to find out what we humans are.

The fact is that when we enter the ocean we are entering the world of the shark and we must respect them. This respect can only be gained through education and understanding. After all, when a lion attacks someone in the savanna it is commonly accepted that the human was likely at fault for entering the lions domain and breaching its comfort zone. When hikers enter bear country they recognize the risk of running into a bear and thus take precautions to avoid conflicts with the bear. So why not give the same respect to sharks when we enter their world.


Discovery Channel. http://dsc.discovery.com/sharks/shark-o-nator/

National Geographic. http://news.nationalgeographic.com/news/2005/06/0613_050613_sharkfacts.html