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Homing in Pigeons
Homing behavior in pigeons, Columba livia, is interesting because pigeons find their way home from unfamiliar sites up to thousands of kilometers from their roost. Pigeon races may feature releases of birds from France, for example, which then find their way home to sites in England or the Netherlands. The extraordinary reliability of homing pigeons makes them excellent subjects for studies of navigation.
How do pigeons find their way home when deposited in an unfamiliar location? To do this, they must have two kinds of information. The first, called "map sense" is their geographic location. The second, "compass sense" is the bearing they need to fly from their new location in order to reach their home. If either information source is disrupted, then homing fails or is delayed.
THE MAP SENSE
In familiar surroundings--locations from which pigeons have previously homed or landscapes through which they have flown--landmarks play a predominant role in homing. Pigeons learn visual
features of the landscape and use these visual features to determine their current position (map location) relative to their roost.
While pigeons clearly use visual landmarks, because pigeons orient better in familiar landscapes when other sensory inputs, such as olfaction, are eliminated, direct tests of landmark usage are diffiicult. Experiments manipulating visual landmarks are generally not feasible. One can hardly bulldoze mountains or cut forests as part of an experimental design, and interference with the eyes, such as using contact lenses, may be so much of a general disruption to the pigeon that it confouds tests of landmark perception in orientation.
How do pigeons produce a map sense when they are released in a completely unfamiliar location? The answer is that they use olfactory cues. In their roost, they associate odors with wind directions. When released, they assess the odor of their new location and extrapolate the map location from their roost-gained knowledge of winds and odors.
Pigeons in visually unfamiliar territory whose sense of smell has been disrupted (by cutting olfactory nerves or treatment of the nasal passages with zinc sulfate solution) have a great deal of difficulty homing. Similarly, if the roost is blocked from winds and provided with filtered air, homing fails. Pigeons may home better if they have some time to olfactorily experience their new surroundings prior to release.
One orientation mechanism that seems to have been experimentally eliminated is path integration. There is no evidence that pigeons track their movement when being transported in cages and then use path integration to determine the distance and direction needed to reach home. Tests of this possibility involve eliminating sensory inputs during transport. Because this conclusion relies on a negative result (continued orientation ability in the absence of a sensory input) there is a small possibility that pigeons use an unknown (and consequently experimentally uncontrolled) sensory input for path integration during transport.
THE COMPASS SENSE
The primary compass information of pigeons comes from the position of the sun in the sky. By integrating their internal clock with the sun's position, they compensate for the apparent
movement of the sun across the sky. Pigeons whose time sense is shifted by keeping then under artificial lights display incorrect orientations when released. For example, if "sunrise" comes for
the pigeons 6 hours prior to actual sunrise, then their orientation is shifted counterclockwise. If their "sunrise" is later than the actualy sunrise, then their orientation shifts
Like migrating birds, the pigeon's sun compass interacts with a magnetic compass. Under some conditions, experimental modification of the magnetic field around pigeons causes problems in homing.
Experiments with clock shifts and magnetic disruption often do not interfere as much as expected with homing. This is because the olfactory and landscape information used in establishing their map sense can be used to correct for compass misinformation.
Another possible source of landscape information is the pattern of ultrasonic reflections from mountains. Ocean waves generate infrasound which then reverbrates through the atmosphere. However, the only evidence for use of infrasound is the inference that sonic booms from jets may have disrupted pigeon races; the hypothesis is that the sonic booms impaired the pigeons' hearing, causing them to be unable to use ultrasound in orientation.
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Published : Wednesday, November 09, 2011
TUGUEGARAO, Cagayan – A total smash.
Due to bad weather, no birds – young and old — made it to the required minimum speed of 700 meters per minute, resulting to a total smash race in the fourth lap of the Philippine Homing Pigeon Association (PHA) North Race 2011 here last Nov. 6.
PHA president Jaime Lim said birds were supposed to be released at 6:30 a.m. on Nov. 6, but had to be delayed due to bad weather.
Racing chairman Nelson Chua has the right to hold the release of birds for a maximum of two hours.
By 8:30 a.m., Chua has no choice but to liberate a total of 856 birds — 630 young birds and 226 old birds — despite the bad weather, resulting into a total smash, meaning no birds made it to the required minimum speed of 700 meters per minute on that race day.
A total of 1, 495 bands for super set category and 220 bands for millennium category were distributed.
Out of the 1,495 super set birds, only 248 birds qualified.
On the other hand, only 55 out of 220 millennium birds qualified.
The said birds and the name of members:
Rey So — 4; Victor Tan — 2; Paul Ung — 4; Egay Yap — 5; Wilson Tiu – 1; Jaime Lim – 4; Vicente Ngo – 1; Apa Loft – 1; Harry Sy – 2; Mary Keyser – 2; Henry Tan – 1; Burlington Loft – 3; Albert Lim – 2; Kerby Chua – 2; Jerry Tan – 3.
Last week, Emmanuel Go completed a rare sweep in the old and young birds categories during the third lap held in Vigan, Ilocos Sur.
Go’s blue bar cock out of Seahaven’s stock cock (Van den Broucke and Valentino cross Johnson Si’s Van Den Broucke hen with PHA-11-9034857, made a speed of 1193.477 meter per minute to capture top honors in the young birds category.
Two-time winner Paquito Ngo clinched runner-up honors with his blue cheque white flight hen out of Pure Joseph Van Den Broucke strain banded PHA-11-9036816 with a speed of 1182.015 meter per minute
Third place went to Harry Lau’s blue cheque cock Andre Lietar cross Joseph Van Den Broucke strain with a speed of 1180.633 meter per minute.
In the young birds bracket, Go also stamped his class with his PHA- 11-9012577 blue bar cock Roger Florizone cross Seahaven’s Stock hen (Schlomer).
The fifth lap will be held in Laoag, Ilocos Norte on Nov. 13.
Completing the busy PHA schedule are the sixth lap in Burgos, Ilocos Norte on Nov 20; and seventh lap in Aparri, Cagayan on Nov. 27.