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Posts Tagged ‘birds’


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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Seychelles Warbler Cooperative Breeding

July 2nd, 2014 by Alyson

This is my added edit to the Seychelles Warbler wikipedia page. I added the section for Cooperative Breeding that can be found here: https://en.wikipedia.org/wiki/Seychelles_Warbler#Cooperative_Breeding_Habits

Cooperative Breeding

Seychelles Warblers demonstrate cooperative breeding, a reproductive system in which adult male and female helpers assist the parents in providing care and feeding the young. The helpers may also aid in territory defense, predator mobbing, nest building, and incubation (females only).[1] Breeding pairs with helpers have increased reproductive success and produced more offspring that survived per year than breeding pairs with the helpers removed.[2] Helpers only feed the young of their parents or close relatives and do not feed unrelated young. This is evidence for the kin-selected adaptation of providing food for the young. The indirect fitness benefits gained by helping close kin are greater than the direct fitness benefits gained as a breeder. This could be evidence for the kin-selected adaptation of providing food for the young.

On high-quality territories where there is more insect prey available, young birds were more likely to stay as helpers rather than moving to low-quality territories as breeders.[3] On low quality territories, having a helper is unfavorable because of increased resource competition. Females are more likely to become helpers[4], which may explain the adaptive sex ratio bias seen in the Seychelles warblers. On high quality territories, females produce 90% daughters; on low quality territories, they produce 80% sons. Clutch sex ratio is skewed towards daughters overall.[5] When females are moved to higher quality territories, they produce two eggs in a clutch instead of a single egg, with both eggs skewed towards the production of females. This change suggests that Seychelles Warblers may have pre-ovulation control of offspring sex ratio, although the exact mechanism is unknown. (more…)

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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…)

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Whooper Swan Signaling Behavior

May 30th, 2014 by vld3

 

Originally, the wikipedia page for Whooper Swans focused on their feeding habits and distribution, but focused very little on the behavior of these swans. I added this information about Whooper Swan behavior to the page: http://en.wikipedia.org/wiki/Whooper_Swan#Distribution_and_behaviour.

When Whooper Swans prepare to go on a flight as a flock, they use a variety of signaling movements to communicate with each other. These movements include head bobs, head shakes, and wing flaps and influence whether the flock will take flight and if so, which individual will take the lead. Whooper Swans that signaled with these movements in large groups were found to be able to convince their flock to follow them 61% of the time.  In comparison, swans that did not signal were only able to create a following 35% of the time.  In most cases, the Whooper Swan in the flock that makes the most movements (head bobs) is also the swan that initiates the flight of the flock – this initiator swan can be either male or female, but is more likely to be a parent than a cygnet. Additionally, this signaling method may be a way for paired mates to stay together in flight. Observational evidence indicates that a swan whose mate is paying attention to and participates in its partner’s signals will be more likely to follow through with the flight. Thus, if a Whooper Swan begins initiating flight signals, it will be less likely to actually carry through with the flight if its mate is not paying attention and is therefore less likely to join it.

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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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