ABSTRACT
Farmers in the Paranapanema Valley (São Paulo, Brazil) have reported problems with flocks of Eared Doves (Zenaida auriculata) eating sprouting soybeans. In this region these birds breed colonially in sugar-cane, and eat four crop seeds, using 70% of the dry weight, in the following order of importance: maize, wheat, rice, and soybeans. Three weeds (Euphorbia heterophylla, Brachiaria plantaginea, and Commelina benghalensis) were important. This information suggests that the doves adapted particularly well to the landscape created by the agricultural practices in the region, exploiting many available foods.
Agricultores no médio Vale do Paranapanema têm relatado problemas com bandos de pombas (Zenaida auriculata) que se alimentam de cotilédones de soja na época do plantio. Na região do município de Tarumã, SP, essas aves se reproduzem em uma colônia situada em um canavial, e sua dieta é composta de 70% do peso seco por 4 grãos cultivados (em ordem de importância: milho, trigo, arroz e soja). As sementes de três invasoras (Euphorbia heterophylla, Brachiaria plantaginea e Commelina benghalensis) são importantes. Essa informação sugere que as pombas se adaptaram particularmente bem à paisagem criada pelas práticas agrícolas da região, aproveitando vários alimentos oferecidos.
ABSTRACT
Farmers in the Paranapanema Valley (Sä¯áPaulo, Brazil) have reported problems with flocks of Eared Doves (Zenaida auriculata) eating sprouting soybeans. In this region these birds breed colonially in sugar-cane, and eat four crop seeds, using 70 percent of the dry weight, in the following order of importance: maize, wheat, rice, and soybeans. Three weeds (Euphorbia heterophylla, Brachiaria plantaginea, and Commelina benghalensis) were important. This information suggests that the doves adapted particularly well to the landscape created by the agricultural practices in the region, exploiting many available foods
Subject(s)
Animals , Columbidae , Diet , Brazil , Breeding , Cotyledon , Crops, Agricultural , Edible Grain , Seeds , Glycine maxABSTRACT
The sun is known to guide homing pigeons as a priority cue. The literature indicates that under total overcast conditions pigeons rely on a backup mechanism akin to the magnetic inclination compass for which there is much laboratory evidence in migratory birds. Total overcast conditions are not favorable for orientation research in the State of Sao Paulo, Brazil. The orientation of homing pigeons raised near the tropic of Capricorn was therefore observed around the time of the December solstice, when the sun culminates directly overhead, with a consequent interruption of the sun compass for a short time every day. In these experiments, carried out between 1981 and 1993, local geomagnetic field inclination was -25 degrees Celsius to -29 degrees Celsius 30', so that a functioning magnetic inclination compass should have been available to the birds. Whereas the birds released with sun to zenith angles between 10 degrees Celsius and 30 degrees Celsius were well oriented, both in the morning (99 vanishing bearings) and in the afternoon (143 vanishing bearings), those released with the sun less than 5 degrees Celsius away from the zenith showed random orientation (105 vanishing bearings), with no evidence of an alternative magnetic compass mechanism.
Subject(s)
Animals , Columbidae/physiology , Orientation/physiology , Solar Activity , Smell/physiologyABSTRACT
Homing pigeons must keep track of the seasonal variations in the sun's daily motion to use the sun as a reference. A delay of seven weeks in such updating of their ephemerides was previously interpreted as being the cause of the behavior of control pigeons studied near the equator in September, when birds released in the morning flew anomalously to the right of birds released in the afternoon. Demonstration of the chronic existence of a delay was obtained by observing that the anomaly was still present but inverted in sign in March, when the pigeons released in the morning flew to the left of those released in the afternoon