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Move that Head: The Behavior of Head-Bobbing in Rock Pigeons

July 4th, 2014 by svn2

 

As I strolled through Hermann Park on a sunny but chilly afternoon, I noticed a huge flock of birds flying down to the edge of the park’s lake from a tall, bare tree that they were resting in. I sat at a bench to watch these birds that seemed to stick together as they flew or pecked on the ground. Although I was watching these birds at the park, I knew that I had seen them around the city, especially at the MetroRail station, gathering at areas where they knew they could get food.  These birds had plump bodies covered in light grey feathers with two black bands on their sometimes speckled wings. However, their small, round heads and necks were covered in dark grey feathers with traces of iridescent purple and green.  With red eyes, they stared at their surroundings while walking on their red legs. These birds were none other than Columba livia, also known as the rock pigeon.

Rock pigeon. Photo by Razvan Socol.

Rock pigeon. Photo by Razvan Socol (CC BY-SA 3.0).

As I observed the rock pigeons, these birds behaved as they usually did whenever I saw them. They flew or walked, pecking the ground for food; however, I saw a behavior that I had never noticed before and that intrigued me: the bobbing of their heads. As the rock pigeons walked, their heads seemed to slowly move back and forth. As I chased after them, the pigeons would walk quickly with their head rapidly bobbing back and forth, most likely feeling threatened.  This made me wonder, “Why do the pigeons bob their heads while walking?” (more…)

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Manduca sexta

June 18th, 2014 by svn2

 

The Wikipedia article for Manduca sexta, or the tobacco hornworm, contained information about its lifecycle. However, no information was provided about its behavior even though there has been recent research about its behavior. I added a Behavior section in the Wikipedia article found here: https://en.wikipedia.org/wiki/Manduca_sexta.

Manduca sexta (Tobacco hornworm). Photo by Daniel Schwen (CC BY-SA 4.0).

Behavior

 Feeding

 Tobacco hornworms are facultative specialists; the larvae can grow and develop on any host-plants. However, the larvae prefer solanaceous plants, such as tobacco and tomato plants. On these types of plants, larvae grow and develop faster. The lateral and medial sensilla styloconia, which are sensory receptors, on their mouthparts help them to identify solanaceous plants by recognizing indioside D, a steroidal glycoside found in those particular plants (del Campo et al., 2001). [1] Tobacco hornworms are considered pests because they feed on the upper leaves of tobacco plants and leave green or black droppings on the plants. As adults, they do not damage the plants since they feed on nectar. [2]

Tobacco hornworm larvae prefer humid environments. When dehydrated, tobacco hornworm larvae will move towards a source of water or to an area with a high relative level of humidity. They use their antennae to locate water to drink (Rowley and Hanson, 2007). [3]

Defense

Nicotine is poisonous to most animals that use muscles to move because nicotine targets the acetylcholine receptor, an important neuromuscular junction. However, the tobacco hornworm is capable of metabolizing nicotine from the tobacco plant and using nicotine as a defense against predators. It possesses a gene called cytochrome P450 6B46 (CYP6B46) that converts nicotine into a metabolite. About 0.65% of nicotine metabolites are transported from the gut to the hemolymph, where they are reconverted to nicotine and released into the air from the tobacco hornworm’s spiracles. The emitted nicotine is used as a way to deter spiders, a practice known as “toxic halitosis.”  In one study, tobacco hornworms that fed from nicotine-deficient plants or expressed low levels of CYP6B46 were more susceptible to wolf spiders predation (Kumar et al., 2013). [4] (more…)

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Geophagy

June 9th, 2014 by asa4

 

Geophagy is the behavior of consuming earth, clay, or soil-like materials. This behavior has been noted in many species including humans. My contribution to the Wikipedia page on Geophagy (http://en.wikipedia.org/wiki/Geophagy) included specific behaviors of geophagy in primates and bats.

Many hypotheses exist to explain the importance of geophagy in bats and primates2,3. Some documented benefits of geophagy include nutrition, detoxification, and benefit as an antimicrobial and anti-parasitic agent; however, the reasons for geophagy are largely species specific1, 3.

PRIMATES:

Krishnamani and Mahaney evaluated various hypotheses that could lead to maintained geophagy in different species of primates including Japanese macaques and chimpanzees2. Reasons for geophagy are largely dependent on the species as well as the habitat. For instance, mountain gorillas demonstrate geophagy as a result of an increased need for iron.  Iron supplementation from the soil helps to meet the demands of decreased oxygen partial pressure at high altitudes2.

BATS:

There has been great debate over whether geophagy in bats is primarily motivated by nutritional supplementation or by detoxification. It is known that some species of bats regularly visit mineral or salt licks to increase mineral consumption. However, Voigt et al. 2008 demonstrated that both mineral- deficient and healthy bats visit salt licks at the same rate3. Therefore, it would seem that mineral supplementation is not the primary reason for geophagy in bats. Additionally, it was found that bat occurrence at salt licks increased during periods of high energy demand. Voigt et al. 2008 concluded that the primary purpose for bat presence at salt licks is for detoxification purposes, compensating for the increased consumption of toxic fruit and seeds3. This was shown to be especially evident in lactating and pregnant bats as their food intake increases to meet higher energy demands3. (more…)

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Rice’s Pet Squirrels

June 4th, 2014 by nyn1

 

The gray squirrel, Sciurus carolinensis, is a creature that is very well known across Rice University for being a little too friendly with Rice students. The squirrels here seem to have habituated themselves to a certain lifestyle here that has reduced their levels of alertness and actually changed the way that the squirrels here on campus forage for food.

Rice Squirrel with a Waffle. Courtesy of ricesquirrels.tumblr.com

Upon watching the gray squirrels, I realized that the squirrels here at Rice are the same species of the squirrels that I have observed living around my home, which happens to be a mere 30 minutes from Rice, however, they have striking differences. The squirrels that I noticed here at Rice were very bold. (more…)

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Communication and Scrounging in Grackles

May 26th, 2014 by ss55

 

The common grackle, or Quiscalus quiscula, may seem little more than a pest. However, I found that these birds made a surprisingly good study for some of the basic principles of animal behavior.

My first observations were on a cold, cloudy afternoon in Rice University’s west parking lot. A small group of birds was perched on the roofs of several cars. Grackles look a bit like small, lanky crows, with longer legs and tail. They are sexually dimorphic, meaning that there are distinct differences between the sexes. Male grackles are an iridescent blue-green-purple with hints of copper—rather oddly like a patch of gasoline in a parking lot. Females, as we can expect in birds, are much blander, with dull brown bodies and dark-capped heads. Because of this difference, I could tell that there was a mix of sexes in the group—three males and three females.

Male grackle, Quiscalus quiscula. Photo credit to safariari on flickr, used under Creative Commons license (CC BY-NC-SA 2.0).

As the birds hopped and shifted on top of the cars, I noticed that they made several distinct sounds. (more…)

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Food For Thought

May 21st, 2014 by asa4

 

The Houston Zoo has many beautiful species held in captivity, including Phoenicopterus ruber, commonly referred to as the American flamingo. I observed a flock of thirty flamingos for foraging behavior on Saturday, February 1st, at 11:30 am. Flamingos are well cited as filter feeders, using their bills and tongue movements to pump water containing food through structures in the beak that allow for filtering (Jenkin 1957).  I observed similar feeding behaviors in both juvenile and adult flamingos. The flamingos placed their beaks in the water and created a vibration, which allows the flamingos to sift through the water. Water waves could be seen as the birds peripherally placed their beaks on the water surface. Occasionally, I observed that a bird would put its head under water and move it in a circular formation around a central point.  This behavior has been described previously as “jig movements” (Jenkins 1957). Based on my observations, this flamingo behavior is a method by which to disturb the bed of the pond. Members of the flamingo flock surprisingly demonstrated minimal variation in their feeding styles. However, I noticed that the juvenile grey flamingos spent much less time foraging for food in comparison to the adult flamingos within the thirty minutes of observation. Instead, the juvenile birds spent more time on land observing and standing next to the adult flamingos. This observation is supported by a study concluding that most flamingo species feed in large flocks (Bildstein et al., 1991).

The flamingos I observed were kept in captivity, so the feeding behavior noted may have been different from what would be observed in the wild. (more…)

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Group Living

May 10th, 2014 by ss55

 

This post is an edit that I wrote to expand on the “Living In Groups” section on Wikipedia’s “Ethology” page. You can visit the page here.

Benefits and costs of group living

One advantage of group living can be decreased predation. If the number of predator attacks stays the same despite increasing prey group size, each prey may have a reduced risk of predator attacks through the dilution effect1. Additionally, a predator that is confused by a mass of individuals can find it more difficult to single out one target. For this reason, the zebra’s stripes offer not only camouflage in a habitat of tall grasses, but also the advantage of blending into a herd of other zebras2. In groups, prey can also actively reduce their predation risk through more effective defense tactics, or through earlier detection of predators through increased vigilance1.

Another advantage of group living can be an increased ability to forage for food. Group members may exchange information about food sources between one another, facilitating the process of resource location1.  Honeybees are a notable example of this, using the waggle dance to communicate the location of flowers to the rest of their hive3. Predators also receive benefits from hunting in groups, through using better strategies and being able to take down larger prey1. (more…)

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A City Way to Acquire Food

May 6th, 2014 by amm18

 

As I saw the animal approach me, I froze just like the icicles that frigid morning. Then the thought crossed my mind, what if it tries to climb me like a tree? Luckily it departed shortly after with no such attempt. It did however leave me wondering why did it get so close to me when most encounters with said animal cause it to scurry away?

One thing was made certain in our encounter: which species, or type, of squirrel it was. Year round my current location is inundated with both grey squirrels and fox squirrels—which both have grey fur covering most of their bodies; thus it was essential to see the squirrel’s secondary color for identifying purposes. Perched up next to me on its hind legs, the squirrel provided the perfect opportunity. As it sat there, an orange color was easily detected. Fox Squirrel! To the scientific community it is known as Sciurus niger.

Fox Squirrel

Fox Squirrel. Photo by Benny Mazur (CC BY 2.0).

The extent of my encounter with the fox squirrel could not have lasted more than 30 seconds. (more…)

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Social Learning in Humpback Whales

May 2nd, 2014 by clk5

Sometimes, natural events happen that lay a great backdrop for scientists to learn more about the natural world. In 2007, New England’s humpback whales all across the population were preforming a new technique that had originated only 27 years earlier. Jenny Allen and her colleagues took this opportunity to determine how behaviors are spread through a population. In April of 2013, these scientists published a report called “Network-Based Diffusion Analysis Reveals Cultural Transmission of Lobtail Feeding in Humpback Whales” in Science, which looked into this new behavior and how it became so widespread in the New England humpback whale population.

Before 1980, the humpback whales of the New England area primarily preyed on herring. When the herring population crashed in this area in the early 1980’s, the whales turned to a new fish as their primary prey: the sand lance. After this change in primary prey, a whale was seen preforming an all-new foraging technique, wherein it slapped the surface of the water right before eating. This technique creates bubbles underwater that group the sand lance together into a cluster, which makes it easier for the whales to hunt them. By 2007, forty percent of the population was using this technique. Allen and her colleagues hypothesized that the high prevalence of the technique was due to either social learning or widespread individual discovery. (more…)

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Foraging from Caches

April 28th, 2014 by akm6
File:Sciurus niger (on fence).jpg

An eastern fox squirrel (Sciurus niger). Image by Markus Krötzsch (CC BY-SA 3.0).

I observed the eastern fox squirrel, Sciurus niger, at various locations on the northern end of Rice University campus on February 3, 2014 in the early afternoon starting at 2:20 pm. On this day the skies were grey but not cloudy and the temperature was 46 degrees Fahrenheit. The wind was not that strong, but still very few squirrels were out. The squirrel habitats I observed were the woody and grassy areas of campus in front of the Lovett Hall building along Main Street. I observed squirrels in areas near human traffic such as university bus stops and in areas more isolated from human contact. During observation, I was initially at least 10 feet away from the squirrel subject at all times. However, there were instances when the squirrels traveled towards me in my direction.

I was most intrigued by a pair of squirrels in a grassy area by the bus stop that were both initially digging into the dirt and grass. The two squirrels were in their separate patches about eight feet apart and they were using their forepaws to remove the dirt from the ground. The digging action was very rapid and vigorous, as I could hear them scraping the grass and dirt away. Sometimes, the squirrels would stop digging and move a few inches and dig another hole. At other times, the squirrels would stop and put something into their mouths and start chewing. I assumed these objects to be cached food; however, I could not determine what type of food it was from the distance I was standing. The reason I believe the objects to be cached food is because the squirrels were digging in the grass for it, where no other types of plants besides the grass were growing. If the squirrels were eating grass roots, then I believe they would not have had to dig several holes in their respective grassy patches to search for the roots. Therefore, I believe they were foraging on previously stored foods. I saw this same digging/searching and eating behavior in two more squirrels that I observed that day.

What would cause the squirrel to store food? (more…)

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