Diet of Eared Doves (Zenaida auriculata, Aves, Columbidae) in a sugar-cane colony in South-eastern Brazil

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.

Diet of Eared Doves (Zenaida auriculata, Aves, Columbidae) in a sugar-cane colony in South-eastern Brazil

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

The speed of pitch resolution in a musical context.

In five experiments, we investigated the speed of pitch resolution in a musical context. In experiments 1-3, listeners were presented an incomplete scale (doh, re, mi, fa, sol, la, ti) and then a probe tone. Listeners were instructed to make a rapid key-press response to probe tones that were relatively proximal in pitch to the last note of the scale (valid trials), and to ignore other probe tones (invalid trials). Reaction times were slower if the pitch of the probe tone was dissonant with the expected pitch (i.e., the completion of the scale, or doh) or if the probe tone was nondiatonic to the key implied by the scale. In experiments 4 and 5, listeners were presented a two-octave incomplete arpeggio, and then a probe tone. In this case, listeners were asked to make a rapid key-press response to probe tones that were relatively distant in pitch from the last note of the arpeggio. Under these conditions, registral direction and pitch proximity were the dominant influences on reaction time. Results are discussed in view of research on auditory attention and models of musical pitch.

Diet of eared doves (Zenaida auriculata, Aves, Columbidae) in a sugar-cane colony in South-eastern Brazil.

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.

Backup compass mechanisms in pigeon orientation with the sun in the zenith.

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 São 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 culminated 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 to -29 degrees 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 and 30 degrees 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 away from the zenith showed random orientation (105 vanishing bearings), with no evidence of an alternative magnetic compass mechanism.

Backup compass mechanisms in pigeon orientation with the sun in the zenith

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.

Orientation in birds. The sun compass.

The sun compass was discovered by G. Kramer in caged birds showing migratory restlessness. Subsequent experiments with caged birds employing directional training and clock shifts, carried out by Hoffman and Schmidt-Koenig, showed that the sun azimuth is used, and the sun altitude ignored. In the laboratory, McDonald found the accuracy to be +/- 3 degrees(-)+/- 5 degrees. According to Hoffmann and Schmidt-Koenig, caged birds trained at medium northern latitudes were able to allow for the sun's apparent movement north of the arctic circle, but not in equatorial and trans-equatorial latitudes. In homing experiments, and employing clock shifts, Schmidt-Koenig demonstrated that the sun compass is used by homing pigeons during initial orientation. This finding is the principal evidence for the existence of a map-and-compass navigational system. Pigeons living in equatorial latitudes utilize the sun compass even under the extreme solar conditions of equinox, achieving angular resolution of about 3 degrees in homing experiments. According to preliminary analyses, the homing pigeons' ephemerides are retarded by several weeks (Ranvaud, Schmidt-Koenig, Ganzhorn et al.).

Seasonal variation in the orientation of homing pigeons: new evidence for a latency in the sun compass.

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.

Seasonal variation in the orientation of homing pigeons: new evidence for a latency in the sun compass

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