Compass Bearings Hypothesis
Suns' Azimuth Hypothesis
Expansion-Contraction Hypothesis
Never Go Back Hypothesis
Analyses of Pooled Field Data: Hypothesis Testing |
Hypothesis Testing: Comparsions of mean bearings to
theoretical bearings, theoretical directions, for the pooled data for the 1978, 1979, and
1981 Monarch butterfly (Danaus plexippus) migrations |
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Mean Bearing ± 95% Confidence Intervals overlaps with the: |
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Wind |
Number |
Mean Bearing |
95% C.I. |
Great Circle Route |
Magnetoclinic Route |
North |
53 |
185° (S) |
±8° |
NO |
NO |
Northeast |
64 |
229° (SW) |
±7° |
YES |
YES |
East |
150 |
247° (WSW) |
±5° |
NO |
NO |
Southeast |
131 |
257° (WSW) |
±5° |
NO |
NO |
South |
15 |
237° (WSW) |
|
YES |
YES |
Southwest |
35 |
143° (SE) |
±52° |
NO |
NO |
West |
20 |
128° (SE) |
±29° |
NO |
NO |
Northwest |
107 |
153° (SSE) |
±5° |
NO |
NO |
Table X** Adapted from Gibo, D. L., 1990
Definitions of abbreviations and symbols: N = North, NE = Northeast, E = East, S = South, SW = Southwest, WSW = West-Southwest, etc., C.I. = Confidence Intervals.
Comments
- Butterflies flying in Northeast winds and South winds had Mean Bearings that
could not be distinguished from either the local Great Circle Route or the Kiepenheur and
Schmidt-Koenig Magnetoclinic route.
- The problems of small sample size, large Angular deviation (Table II), and large Confidence Intervals
for the the South wind group indicate that the results should be considered very
tentative. In other words, the mean bearings for the South wind group, ±39°,
will include any theoretical bearing that falls within the range of 276° (W) to 198°
(SSW).
- It is important to keep in mind that for the Northeast group, both theoretical directions fall in the downwind sector. Even if D. plexippus were simply circling in thermals, and 64% were doing this (Table VII), they would still be displaced in approximately the appropriate direction for the great Circle Route and/or the Kiepenheur and Schmidt-Koenig Magnetoclinic Route.