Rice University logo
 
Top blue bar image
 

Posts Tagged ‘predation’


The Beauty of Butterflies

July 11th, 2014 by San-Pei Lee

Butterflies in Cockrell Butterfly Center (Greta oto , Dryas iulia, Morpho peleides, Caligo memnon, Parides iphidamas, Attacus atlas). Photos by San-Pei Lee.

Have you ever found yourself entranced by the beauty of a fluttering butterfly? The Cockrell Butterfly Center (Houston Museum of Natural Sciences) is a marvelous place to stay for a long duration to observe butterflies’ behaviors or to just enjoy the beauty of butterflies. The simulated environment is as close to a tropical rainforest as one can get to in an urban area. The temperature and humidity of the rainforest conservatory was rather high (temperature around 85 degrees Fahrenheit) to accommodate the butterflies and tropical plants. Sunlight penetrated through the glass walls, and a waterfall filled the air with nature’s sounds. There were even smoothie-looking juices, dried fruit mixes, and nectar-filled sponges provided vitamins and minerals for the butterflies.

There were several species of butterflies fluttering all around and stopping for nourishments or rest. The ones I found most intriguing, all of which were in the family Nymphalidae, were the Blue Morpho (Morpho peleides), Giant Owl (Caligo memnon), Julia Longwing (Dryas iulia), and Glasswing (Greta oto). The Glasswing was truly amazing in that it really had transparent wings, and its small size and quick movements made it even harder to find. These physical traits are most likely adaptive for hiding and escaping from predators, such as birds and spiders (Binetti et. al, 2009). On the other hand, the Julia Longwing was bright orange, most likely demonstrating mimicry, where its bright color warns predators of its toxicity. Also, there was a passion flower potted plant on a bench that attracted countless Longwings, in particular the Julia Longwings. The longwings most likely found the passion flower plant, perhaps with pheromones (Maida and Zeisman, 2001), or secreted hormones, that the butterflies probably recognized from when they were caterpillars, and deposited an egg as many times as possible to ensure high reproductive success. I noticed that butterflies preferred to hang upside-down when laying eggs on the undersides of leaves, probably as protection for the eggs against predators like ants. An example of an even more clever physical adaptation is the Owl’s “owl eyes”. I sighted one owl-eyed spot on each wing so that when the Owl rests and closes it wings together, it looked like an owl. This appearance fools and scares away predators (Frederiksen, 2008). The Owl is crepuscular, signifying that it is mostly awake around dawn and dusk (Frederiksen, 2008). This butterfly’s brown owl-like appearance seems very fitting for it to be crepuscular and almost nocturnal or active at night, like the owl bird it imitates. I found a few resting on the rock walls, and when they did fly, it was an awkward, bat-like flight. My favorite was the Blue Morpho because its wings reflected a beautiful, glittering blue, another foil for predators. This large butterfly flew fast but smoothly, and I observed a lot of them playing and chasing each other. Something interesting about the Blue Morpho is that the undersides of its wings are similar to the Owl’s with dull colors and small eye-looking spots, which is most likely an added protection. (more…)

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…)

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…)

Feather Ruffling in Black-bellied Whistling Ducks

June 11th, 2014 by cer7

 

Birds do a variety of behaviors to keep warm, avoid predators, mate, and find food. In my observations, I watched the Black-bellied Whistling Duck, or Dendrocygna autumnalis. This bird is a type of waterfowl native to parts of Mexico and South America, although they can be seen in the southern United States during the summer (“Black-bellied Whistling-Duck”). The Black-bellied Whistling Duck is brown with a grey head and a black underbelly. Its feet and beak are pink. The Whistling Duck gets its name from the whistling noise it makes. I observed flock of these birds at around 4:30 pm on a rainy cold day in Herman Park. The temperature outside was about 40°F, and the rain was very light.

The flock of ducks I observed numbered about ten, and they were walking along the path by the large pond in Herman Park. The behavior I thought was interesting happened a few times during my time observing these ducks. First, a duck would get a little taller in stance, and hold its wings out to the side. Then it would flap its wings, put them down, and ruffle its feathers a little as its wings shifted back into place. I took the picture below while observing the initial states of this behavior. You can see the raised wings of the Whistling Duck right before it folds them in and ruffles its feathers.

Black-bellied whistling ducks. Photo by Clare Randolph.

This behavior could have a lot of explanations. (more…)

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…)

Texas Minnow Risk vs. Reward Behavior

May 19th, 2014 by vld3

 

Many organisms walk a fine line, balancing their need for food with their need to avoid predation. Minnows in Texas are no exception to this rule. On a cold day (around 50 degrees Fahrenheit) with no precipitation and partial clouds, I observed several minnows on the edge of a local pond (I observed within a foot of the edge of the pond).  The minnows ranged from about two to about four inches long and appeared to be of the same species and of the family Ciprinidae (Nelson, 2000). The pond had algae and debris lining its edge.

While I was watching the minnows, I noticed that they would continually flick around in a very excited manner. Flicking involved very short, fast movements, in which the minnows usually moved less than an inch in a second or less. Usually, this flicking would bring them to the top of the pond, or even closer to the shore. When the minnows moved, they also appeared to be nibbling on the algae in small bites – taking one nibble and then “flicking away”. Additionally, the minnows moved independently, but seemed to stay around the same group of other minnows. Finally, if I moved and a shadow passed over the water, the minnows would dart away. Their darting had them moving quickly, like with flicking, but in longer strokes – when darting the minnows usually moved out of eyesight, but definitely more than a few inches.

While watching the minnows, I developed several hypotheses regarding what evolutionary advantages some of their behaviors may have served. (more…)

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…)

Water ripples in Tungara frog interactions

May 8th, 2014 by ss55

 

When a scientist publishes their research in a journal, the flow of information of doesn’t stop there—science journalism is an important form of communication that makes this research accessible to the average person. Because academic readers and casual readers are very different audiences, differences are necessary in the way that the same information is presented. By comparing a popular science article to its primary source, we can see how a skillful writer can turn research into news.

In a recent study published in Science (Halfwerk et al., 2014), a research team investigated how animals integrate multiple sensory systems when receiving another animal’s signal. The researchers worked with male Tungara frogs, which produce mating calls while sitting in shallow water. Although it was previously known that frogs would respond to a neighboring male’s call (by calling faster, or falling silent in either preparation to fight or flee), Halfwerk and colleagues discovered that the water ripples produced by calling are an important factor—other males were significantly more likely to respond when ripples accompanied a recorded male frog call. If the ripples indicated that the call was outside the male’s territory (about a 15 cm circle), males increase their rate of calling. If the ripples were inside the territory, males more often fell silent as they prepared to fight or yield to the competitor. (more…)