Date: Fri, 31 Jan 2003 23:28:13 -0500 Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding From: Bill Ellis Subject: Comments on the Turkey Point Hawk Watch 2002 Results Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" After seeing the counts for the Turkey Point Hawk Watch, provided by Leslie Fisher in her MDOsprey posting of 12/28/02, a lot of questions popped into my head. 1. Is the decline in number because of the decrease in count hours? 2. Did other hawk watches experience similar declines? 3. How do the proportions of the individual species with large counts compare with the nearby hawk watches at Hawk Mountain and Cape May? 4. How do the proportions of counts of the hawk types (accipiters, buteos, falcons, etc.) compare with other hawk watches? 5. Based on the answers to #3 and #4, is the Turkey Point Hawk Watch like nearby hawk watches, or unique? I did some calculations to try to answer my own questions. (An Excel spreadsheet of these calculations is available directly from me by e-mail.) My proposed answers, with commentary provided by Leslie, the Count Coordinator, follow: 1. The decline in number is partly because of the decrease in count hours, since the counts are not normalized for hours spent counting. The decrease in hours was about 10 percent, while the decrease in total hawks counted was about 24 percent. If the count for 2002 is corrected for the decrease in hours counting, the decrease reduces to just 15 percent. (See the "01-02 Changes" page of the spreadsheet.) Leslie noted that part of the decreased count hours was weather related, such as rain days, and other count sites probably experienced this as well. In general, it was a very wet fall, as well as poor weather patterns in general for migration. Parke John, an experienced observer at Turkey Point, also suggested that the high proportion of novice counters at Turkey Point may cause a low bias in the counts. 2. Hawk Mountain did experience a decline from 2001 to 2002 in the total of the 4 hawks reported to have significant declines at Turkey Point (SS, RT, RS, AK). Turkey Point's decline in the total count for the four hawks was about 26 percent, while Hawk Mountain's decline was 21 percent. For all hawks, Hawk Mountain showed an increase, however, of 38 percent, while Turkey Point's totals dropped as decribed in #1. Leslie thought it was interesting that Hawk Mountain showed an overall increase of 38%; perhaps weather patterns influenced the number of birds choosing a mountain ridge flight path as opposed to a peninsular site such as Turkey Point. 3. The proportion of SS at Turkey Point and Cape May (for 2001; 2002 data were not found) are similar: about 46 percent and 45 percent. The proportion of RT at Turkey Point and Hawk Mountain (for 2002) are similar: about 17 percent and 16 percent. (See the "Proportions" page.) Turkey Point seems to differ a lot from both of the other hawk watches in proportion of TV. I suspect that this may be a counting artifact, because of the difficulty in differentiating migrants from locals at Turkey Point. Leslie suspected that the latter might be correct. She also thought it interesting that Cape May has such a similar percent of SS. A high percent of Turkey Point SS are immature birds. Parke John agrees with Leslie about the TV numbers, and suggests further that the BE numbers are also questionable for similar reasons and Turkey Point's proximity to Conowingo. 4. The proportions of hawk types are shown in the Proportions page. Turkey Point resembles Cape May only for accipiters, and resembles Hawk Mountain only in having a high proportion of buteos. Buteos dominate the count at Hawk Mountain because of huge BW counts; buteos are the second largest group at Turkey Point, but because of large RT counts. Leslie agreed that Turkey Point's negligible BW counts do put it way behind other counts on buteos in general. 5. Turkey Point is unique among the three counts, with few similarities in count proportions. I like that. And Cheers! to Leslie - your effort and your counting team's efforts are very worthwhile! Bill Ellis Eldersburg, Carroll County ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey =======================================================================