Hot or Not?

Where's your hot zone?

A few days of sorting through my field notes and the seasonal summary reports produced the data I wanted. The numbers came out as:

Region	Effort (hrs)	Detections	D/hr
1	50	1	0.02
2	41	0	0.00
3	236	7	0.03
4	182	4	0.02
5	44	0	0.00
Total	553	12	0.02

The overall detection rate was about once per 50 hours. So, on to the question: Is the "hot zone" hot or not? Well, the Rhodes Lake area (region 3) does have the highest detection rate, looking at the raw numbers. And 92% of detections came from regions 3 and 4 (Hushpuckett-Forked lakes). But, 76% of our effort was put in there. I could do a Chi-square on this, but that would be misleading as it would treat each hour of effort as an independent sample, which of course it is not. So I'll just stick to the "O-test." And the significance of the hot zone appears to fail the O-test. At 0.02 D/hr we would have expected 2.6 detections in regions 1, 2, and 5; we had 1. That's not likely be a statistically significant difference however you analyze it.

What about seasonality? Were February and March really more active than the rest of the year? Here are the data grouped by months:

Month	Hours	Detections	Detections/hr
Feb	28	3	0.11
Mar	237	6	0.03
Apr	238	3	0.01
May	42	0	0
Jun	8	0	0
ALL	553	12	0.02

Remember that the February data are all from the last 2 days of the month, representing the flurry of detections that got the whole snipe hunt underway. So that apparent huge spike in February is not necessarily as impressive as it might seem at first glance. The dropoff in detections after March does look real, however. Combining Feb-Mar gives one detection per 29 hours; Apr-Jun averages one detection per 96 hrs. Again rigorous statistics would be hard to calculate, but the "O-test" would suggest this difference is probably real.

What about the absence of detections after April? Is that real? Well, you can't really tell. It's only 50 hours of effort, during which time you might expect 0.5 detections if there was no real drop in detection rates. When you are dealing with count data, an observed value of zero is of course not significantly different from an expected value of 0.5 no matter how you slice it.

Combining the seasonal pattern with the spatial one pretty much erases the "hot zone." Most of the effort in region 1, and nearly all of the effort in regions 2 and 5. happened after the seasonal drop in detection rates. If you allow for this, you can't conclude that there is any real pattern of higher detections in the areas around Rhodes, Hushpuckett, and Forked Lakes than in the rest of the WMA. You can't conclude there isn't either, of course; there just wasn't enough effort put in elsewhere early enough in the season to be able to say either way.

This made the initial strategy for 2009 clear to me. Spread out the effort across the WMA, and see if anything happens. Don't focus exclusively on the "hot zone," because it might not be any hotter than anywhere else. Time would hopefully tell.

**************

My next visit to Moss Island was January 21-23. I developed a rotation of regions, spending the morning in one, the afternoon in another, revolving through all 5 of them. This visit found clear and cold weather, with very nippy nights in the tent. As I said to Scott when he expressed concern about camping in such cold weather, I was just fine at 15F /-10C inside two mummy bags with both tops cinched shut, wearing a stocking hat and two layers of sweats. No problem! The cold weather combined with fluctuating water levels created some intriguing and beautiful effects in the sloughs:



I never managed to catch it on video, but the Winter Wrens liked to forage inside the ice caves formed underneath these hanging ice sheets.

Woodpeckerwise, it still remained relatively quiet. Drumming and vocalizations remained at mid-winter levels, with single-digit counts of Pileateds most mornings and afternoons. As I had noted last year, the woodpeckeriest areas remained regions 2 and 5, among the higher hardwoods with oaks and pecans. The southwest woods were especially a hotbed for Red-headeds, with a tally of 23 in just 3 hours on my final morning at the site.

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