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Archive for the ‘Natural history’ Category


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…)

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…)

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…)

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…)

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…)

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…)

Asian Elephant Parental Care

April 30th, 2014 by clk5

 

I observed three Asian Elephants (Elephas maximus) at the Houston Zoo on a clear, temperate day. I focused my observations on interactions between the three elephants; a mother and her two children. The elephants were held in a large fenced-in enclosure with a pond, grassy areas, and sandy areas. The mother elephant I observed exhibited many examples of well-known elephant parental care strategies.

When I first arrived, only the mother elephant was in the enclosure. She was drinking from the pond when her two children were released into the enclosure one by one. The mother greeted her children by running her trunk over their faces. According to some studies, elephants use this “mouth check” to determine the health and mood of their companion. Scientists believe that elephants have distinct chemical differences in their breath that another elephant can pick up through their trunks (reviewed in Langbauer 2000). The calves also greeted each other in this fashion.

"Elephants-OregonZoo” by StuSeeger is licensed under the terms of the cc-by-2.0.

The elephants seemed to rely heavily on touch throughout my observation. The initial “mouth check” greeting was then followed by many more instances of contact. (more…)

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…)