Normal fluctuations of the geomagnetic field may affect initial orientation in pigeons

Kowalski, Ute; Wiltschko, Roswitha; Füller, E.

doi:10.1007/bf00603843

Cited by 40 publications

(17 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When releasing the pigeons repeatedly at two sites Keeton et al (1974) and Kowalski et al (1988) found close correlations between magnetic K activity prior to release and initial orientation, at least at one of both sites tested. Although their results are difficult to compare with my multilocation study, they suggest a potential !imitation.…”

Section: Relations To Magnetismmentioning

confidence: 99%

See 1 more Smart Citation

Pigeon homing in relation to geomagnetic, gravitational, topographical, and meteorological conditions

Dornfeldt

1991

Behav Ecol Sociobiol

View full text Add to dashboard Cite

Experienced homing pigeons were released at sites unfamiliar to them and with magnetic and gravity anomalies as well as in areas with rather normal fields throughout the FRG (41 releases when sunny, 14 when overcast; Figs. 1-3). The second-order release data were subjected to both univariate and multivariate statistical analysis (stepwise regression, factor analysis). The magnetic field strength and its gradients within the l-km circle around the release site were determined from aeromagnetic maps of the anomalies of magnetic total intensity. Analogous variables were derived from gravity anomaly maps. It was tested whether the pigeons fly along that gradient to minimize the difference between the magnetic or gravity field at the release site and the loft at maximum rate. Further independent variables described magnetic K index, day-to-day variations of the magnetic components, topography, meteorological conditions, the number of the releases the pigeons had done, and the distance.Over magnetic anomalies widely varying in strength (departing -250 nT to 300 nT from normal 600 m above ground), extent, and distance from loft, the pigeons vanished with less deviation from the homeward direction and faster than they did in areas with less irregular fields under sunny conditions; this is in contrast to other studies on magnetic anomalies, except one. At sites of gravity anomalies (15M9 regal), the pigeons were significantly less homeward oriented and homed slower than at less anomalous sites (-9 to 14 mgal).Variables related to gravity were best predictors in 8 and and second predictors in 3 out of 15 regression analyses of the navigational parameters for the releases under sun. Six times the (absolute) amount of the gravity difference between the release site and the loft was selected first (Figs. 7 B, C, 8 B, C). The results suggest gravity to be involved in navigation as the pigeons' distance measure. Homeward directedness declined with increasing amount of the gravity gradient in the first 12 releases under sunny skies as well as when overcast (Fig. 8A). A preferred compass direction towards north-northeast was determined, being closest to the grand mean vector of the ascending gravity gradient (Fig. 6). The analyses failed to show directional preferences as assumed by the hypotheses tested. Temperature and degree of cloud cover provided some information for predicting mean vector lengths and mean vanishing times, respectively. The surface wind component in the homeward direction was correlated with median homing performances.

show abstract

Section: Relations To Magnetismmentioning

confidence: 99%

“…Further variables were the K indices of geomagnetic activity as well as day-to-day variations in the components of the earth's magnetic field; it seemed worthwhile to incorporate them with a view to some correlation with magnetic K activity prior to release (Keeton et al 1974;Kowalski et al 1988).…”

Section: Introductionmentioning

confidence: 99%

Pigeon homing in relation to geomagnetic, gravitational, topographical, and meteorological conditions

Dornfeldt

1991

Behav Ecol Sociobiol

View full text Add to dashboard Cite

show abstract

“…In general, at any location a diurnal variation with an amplitude of some tens of nT occurs; additionally, magnetic storms cause field variations with amplitudes up to hundreds of nT that can last several days. The diurnal variation of the naturally occurring, time-varying geomagnetic field (GMF)-that is, the GMF disturbance level-is measured by each local geomagnetic observatory as the K index (Skiles 1985;Kowalski et al 1988). The K index is a quasilogarithmic measure of the maximum disturbance horizontal component in steps of 0-9 for 3 h (UTC).…”

Section: Introductionmentioning

confidence: 99%

Geomagnetic field modulates artificial static magnetic field effect on arterial baroreflex and on microcirculation

Gmitrov

2006

Int J Biometeorol

View full text Add to dashboard Cite

show abstract

“…Normally its values lie between 1 and 3, 0 representing an unusually quiet period. K values of 4-9 mark magnetic storms [Skiles, 1985;Kowalski et al, 1988]. The K p , or planetary 3 h range index, is defined to be the arithmetic mean of the K values of 13 selected word wide geomagnetic observatories [Mayaud, 1980].…”

Section: Introductionmentioning

confidence: 99%

Geomagnetic field effect on cardiovascular regulation

Gmitrov

Gmitrova

2004

Bioelectromagnetics

View full text Add to dashboard Cite

The goal of the present research was try to explain the physiological mechanism for the influence of the geomagnetic field (GMF) disturbance, reflected by the indices of the geomagnetic activity (K, K(p), A(k), and A(p) indices), on cardiovascular regulation. One hundred forty three experimental runs (one daily) comprising 50 min hemodynamic monitoring sequences were carried out in rabbits sedated by pentobarbital infusion (5 mg/kg/h). We examined the arterial baroreflex effects on the short term blood pressure and heart rate (HR) variabilities reflected by the standard deviation (SD) of the average values of the mean femoral arterial blood pressure (MAP) and the HR. Baroreflex sensitivity (BRS) was estimated from blood pressure/HR response to intravenous (i.v.) bolus injections of vasoconstrictor (phenylephrine) and vasodilator (nitroprusside) drugs. We found a significant negative correlation of increasing GMF disturbance (K(p)) with BRS (P = 0.008), HR SD (P =0.022), and MAP SD (P = 0.002) signifying the involvement of the arterial baroreflex mechanism. The abrupt change in geomagnetic disturbance from low (K = 0) to high (K = 4-5) values was associated with a significant increase in MAP (83 +/- 5 vs. 99 +/- 5 mm Hg, P = 0.045) and myocardial oxygen consumption, measured by MAP and HR product (24100 +/- 1800 vs. 31000 +/- 2500 mm Hg. bpm, P = 0.034), comprising an additional cardiovascular risk. Most likely, GMF affects brainstem and higher neural cardiovascular regulatory centers modulating blood pressure and HR variabilities associated with the arterial baroreflex.

show abstract

Normal fluctuations of the geomagnetic field may affect initial orientation in pigeons

Cited by 40 publications

References 17 publications

Pigeon homing in relation to geomagnetic, gravitational, topographical, and meteorological conditions

Pigeon homing in relation to geomagnetic, gravitational, topographical, and meteorological conditions

Geomagnetic field modulates artificial static magnetic field effect on arterial baroreflex and on microcirculation

Geomagnetic field effect on cardiovascular regulation

Contact Info

Product

Resources

About