Accuracy in Data Collection Exercise: Timing of Flight Patterns in a Day

Accuracy in Data Collection:

Timing of Daily Bee Flight Patterns

By Dylan Voeller and James Nieh

I. Principles introduced in this exercise

A. Importance of weather conditions in bee foraging

B. Data collection using the web

C. Statistical analysis: arithmetic mean

II. Introduction

The activity of bees is not constant throughout the day. Changes in weather (rainy days, cloudy days, sunny days, etc), have an important effect on their flight activity and therefore on pollination on any given day (Roubik, 1989). Many flowers provide the most nectar at certain periods of time and thus changes in weather can affect how flowers are pollinated, and how far bees are willing to fly to pollinate flowers. Consequently, changes in temperature such as those occurring due to global warming, may have an effect on the pollinating activity of bees, and thus have larger ecological effects. This exercise involves using a single variable, the number of bees, to determine the temperature and time period during which a certain species of bee is most active. It also looks at the accuracy of data collection by comparing counts of bees between students.

III. Materials & Methods

· Have students click on the link above to access the video data (you will need the Quicktime Player plugin). There are several different video files for different species at different times of day. We will be adding a real-time webcam, but for now will be adding interesting pre-recorded videos as they become available.

· Allow students to practice recording counts of bees flying out of the hive. Using a pen and paper, have each student create tally marks on a sheet of paper for each bee observed in a one-minute interval.

· Once they are familiar with counting using the video data, have students begin counting bees for the entire length of the video. When the video is finished, have each student report a total for their bee tally.

· Be sure to take note of the temperature, time of day, species, and location recorded in the video.

· Repeat this procedure and for the remainder of the video files.

IV. Sample Results

A. Create a table of bee counts for each species with the different times of day and temperatures the counts took place:

Sample Table 1: Number of bees sp. observed at various times and their corresponding temperatures

Number of Bees Reported by Each Group				Observation Time and Temperature (°F)
	9:00 AM	10:00 AM	11:00 AM	12:00 PM	1:00 PM	2:00 PM	3:00 PM
	60 °F	63 °F	66 °F	70 °F	71 °F	72 °F	68 °F
1	17	23	27	33	35	38	32
2	17	22	26	33	34	36	33
3	16	23	27	33	35	38	32
4	17	21	27	34	33	38	33
5	15	19	27	32	34	36	33
6	18	22	27	32	35	37	31
7	17	22	28	31	36	37	31
8	15	21	29	33	32	35	31
9	15	23	27	33	33	37	31
10	17	19	26	34	35	37	33
11	16	21	27	31	35	38	32
12	18	23	27	32	35	38	32
13	17	21	28	31	36	36	31

Analyzing the Data

Notice that in each column of Sample Table 1, individual measurements differ from one another, but tend to cluster around a certain value. This value is called the arithmetic mean or average. Finding the mean of a group of measurements can help biologists discover patterns in what seems like variable activity. The mean can be found by adding up the individual group counts (x1, x2, x3, . . ., xn) and dividing by the total number of groups for which a count was taken, n.

Mean = ∑x

_______

For example, the mean of column 1 (9:00 AM) in Sample Table 1 would be calculated as follows:

Mean =17 + 17 + 16 + 17 + 15 + 18 + 17 + 15 + 15 + 17 + 16 + 18 + 17 ÷ 13= 215 ÷ 13 =16.54

B. Have students take the arithmetic mean of the group counts for each time interval.

C. Then have students create a graph, plotting the time of day and temperature on the x-axis, and the mean number of bees on the y-axis:

D. Repeat steps B. and C. for each bee species.

Sample Figure 1: Mean number of bees counted as a function of the temperature at a given time of day

V. Sample Discussion Questions

A. What time of day were the bees most active?

B. At what temperature do the bees appear to be most active?

C. Why might the bees be most active at this time of day?

D. What other factors could be influencing the activity of these bees?

E. If global warming raises the temperature of the earth by several degrees, how might the activity of bees and the reproduction of the plants they pollinate be affected?

VI. Sample Conclusions

The bees were most active at 2:00pm and a temperature of 72 °F. It appears that they prefer temperatures around 70 °F; the slope in Figure 1 increases until around 70 °F and begins to decrease at 68 °F. However, it is possible that temperatures higher than 72 °F elicit an even greater level of activity. Outside factors such as humidity, competition by surrounding pollinators, and the abundance or absence of flowering host plants may have also been influencing the observed behavior. From Figure 1 it is not possible to tell what influence warming might have on this population. A factor such as global warming could enhance the activity of the bees or alternately decrease it if, for example, the bees become overheated at higher temperatures.

VII. References

Hampton, R.E., 1994. Introductory biological statistics. Iowa, Wm. C. Brown Communications,

Inc.

Roubik, D.W., 1989. Ecology and natural history of tropical bees. New York, Cambridge

University Press, 514.