Tactics and Vectors 98/99
                           

Home

Table of  Contents

Great Circle Hypotheis  

Magnetoclinic Hypothesis

Magnetic-Latitude Hypothesis

Compass Bearings Hypothesis

Suns' Azimuth Hypothesis

Expansion-Contraction Hypothesis

Always Advance Hypothesis

Never Go Back Hypothesis

 

 

Analyses of Pooled Field Data: Descriptive Statistics


Descriptive statistics for pooled directional data for 1978, 1979, and 1981 Monarch butterfly (Danaus plexippus) migrations in Southern Ontario 

¦ Up   ¦ Tables:  ¦ IIIIII IV,  VVIVIIVIII aVIII bIXX,  XI,   XII  ¦


left arrowarrow leftTable V*

Proportion of migrating Danaus plexippus flying at low (less than 3 m), intermediate (3 m to 29 m), and high (30 m and above) altitudes for eight wind conditions

Directional data were grouped according altitude category and wind direction at the time of the observation.  


Number and percentage of migrating D. plexippus in each altitude category for each wind condition


Wind

N

 Alt. < = 3 m 

  3 m < Alt. < 30 m

Alt. = > 30 m


Num.        %  

Num.         %     

Num.        %    


North

 53

2           3.8

26          49.1 

25         47.2

Northeast

  64 

   7         10.9  

21          32.8 

36         56.3

East

150 

13            8.7  

39          26.0 

  98         65.3  

Southeast

131 

8            6.1

72          55.0 

  51         38.9  

South

15

8          53.3

  5           33.3 

    2         13..3  

Southwest

  35  

6          17.1

12           34.3 

  17         48.6   

West

20

4          20.0

10           50.0 

    6          30.0   

Northwest

107   

3            2.8

35          32.7 

    69          64.5    

Population

575  

51        8.9 

220       38.3  

304       52.9 


* Adapted from Gibo, D. L.  19861990

Definitions of abbreviations and symbols:  N = number in sample, Num. = number in altitude category.   

Comments

  1. Although only about 9% of the population was observed flying within 3 m of the ground,  more that half of the migrants flying in South winds were within 3 m of the ground.  A South wind is a combination of a headwind and a left crosswind to a Southwest course.

  2. The butterflies seldom migratated during periods of Southwest winds, a direct headwind condition.   Most of the observations for the SW wind category were made during one morning when mean wind velocity at 1.5 m was only 0.8 m/s.