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Hi Steve, The answers to your questions can only be obtained from long term, standardized monitoring. John's acoustic work will hopefully continue for many years and provide another source of such long term information. From long term, on-the-ground data I can provide you some answers. The migration pattern of most of the nocturnally migrating song birds that occur in Nova Scotia is 'normally' distributed. That is, their numbers gradually increase to a peak and then gradually decrease. The rate of these increases and decrease vary by species and there are some exceptions. As John's data shows there are species' differences in when the migration peak occurs. Muddying the waters are things such as pre-migration movement, coastal versus interior breeding versus latitude, aberrant weather, age differences in the timing of migration, etc. The length of daylight is the main factor which triggers fall migration. While there will be early, southerly movements of some birds, each species migrates using roughly the same timetable each year. In general, the bulk of song bird migration does not really get going until about the third week of August. The eight weeks from this point onward are when the southward movement peaks will occur. For American Redstarts and Magnolia Warblers, their numbers peak on Brier Island sometime during the last week of August. Common Yellowthroats peak about a week earlier. For comparison, Yellow-rumped Warbler numbers peak in October. This is what the ground data shows. However, John's acoustic data for this year shows something else. It shows peak numbers of these species about two weeks later than these dates. It will be interesting to see if this is repeated in future years and to discuss with John why there might be this difference. All the best, Lance Lance Laviolette Glen Robertson, Ontario -----Original Message----- From: naturens-owner@chebucto.ns.ca [mailto:naturens-owner@chebucto.ns.ca] On Behalf Of John Kearney Sent: Tuesday, September 29, 2015 7:39 AM To: naturens@chebucto.ns.ca Subject: EXTERNAL: RE: [NatureNS] Nocturnal Migration for the Week of 21-27 September 2015 Hi Steve, Thanks very much for your interesting comments. First on the technical side, you can enlarge the tables by clicking on them but I think you mean that they are hard to interpret in table form. I agree, and your comments are very timely. I've been looking for a graphing program that will enable me to make a chronological bar graph such as in found in the data section of eBird. Perhaps Kaleidagraph is the answer, and I will definitely check that out! On the biological side, I am indeed trying to establish some baseline data for nocturnal migration in Nova Scotia. Most of our understanding of migration is based on birds surveyed during stop-over, that is on the ground, and only recently have radar, tagging, and acoustic studies been providing more data on the ecology of birds in the air. There are certainly similarities between what is observed on the ground during the day and what is recorded flying overhead at night. But there are also some very interesting differences. In terms of timing, how the migration schedule of a species relates to its breeding activities, wintering grounds, and its specific migration strategy are all questions for which much more work needs to be done. As many of our migrants bred far north of us and will winter far south of us, their story is certainly a fascinating one, with many more chapters still to come. Thanks again, John -----Original Message----- From: naturens-owner@chebucto.ns.ca [mailto:naturens-owner@chebucto.ns.ca] On Behalf Of Stephen Shaw Sent: September-28-15 22:35 To: naturens@chebucto.ns.ca Subject: RE: [NatureNS] Nocturnal Migration for the Week of 21-27 September 2015 Hi John, The time series for individual species is interesting and presumably why you are collecting the info (?). It looks from your website as if the Magnolia Warbler has risen to an orderly smooth recent peak and will now drop off, while the Am Redstart had an extended early distribution where you may have missed much of the migration, before sampling started 10 August, but it's a bit hard to see. I checked your website and you have an instructive summary table there with daily numbers for each species (or a group of indistinguishable similars), but it 's hard to read easily because it's a table of numbers. Do you also employ a time display function -- a graph for each, made in a graphing spreadsheet like Kaleidagraph (KG, not that expensive), which would be easier to visualize? In KG you can plot one graph and pretty it up laboriously for your ideal presentation, then use that as a graph 'Template' to plot all the others painlessly in exactly the same format from one common spreadsheet (no I'm not a agent for KG, just use it -- maybe other programs can do the same). Or you can put several species into one graph in different colours. You can then plot or display several of the independent graphs lined up together using KG's 'Layout' function for comparison, though I doubt if displaying/printing more than ~6 to a page would be visually useful. Is the idea that Redstarts migrate early because they have run low on their food species, or perhaps because they have now finished breeding/fledging, compared to Magnolia Warblers (or Common Yellowthroats) which may occupy a different niche/finish breeding later? Is it known whether the individual migrating stats line up with what's known of the earlier breeding/fledging timing? Very interesting, anyway -- thanks for showing the data regularly on NatureNS. Steve (Hfx) ________________________________________ From: naturens-owner@chebucto.ns.ca [naturens-owner@chebucto.ns.ca] on behalf of John Kearney [john.kearney@ns.sympatico.ca] Sent: Monday, September 28, 2015 4:40 PM To: naturens@chebucto.ns.ca Subject: [NatureNS] Nocturnal Migration for the Week of 21-27 September 2015 Hi All, Nocturnal migration was light but steady throughout this past week over Carleton, Yarmouth County. A total of 817 calls, representing at least 669 birds, was recorded. Compared to last week, warblers declined from 86% of calls to 68% while sparrows increased from 8% to 24%. Thrushes remained the same at 4% of calls. The most common bird of the week was Common Yellowthroat at 117 calls, followed by White-throated Sparrow (72), and Yellow-rumped Warbler (63). The count of this late warbler was nearly triple what it was last week. Palm Warblers continued in good numbers (55) while there was a noticeable decline in the once dominant Magnolia Warbler from 329 calls last week to 55 calls this week. The unidentifiable to species Melospiza flight call also increased three-fold this week (38 calls). These likely represent mostly Swamp Sparrows at this time in September. The rare bird for the week was a Brown Thrasher at 6:41 am on 22 September. Uncommon warblers included a Pine Warbler at 5:41 am on 28 September. A summary table follows. Additional information can be found at: http://www.johnfkearney.com/Carleton_YarmouthCounty_2015.html. John Species, followed by Total Calls and Estimated Minimum Individuals Common Yellowthroat 117 98 White-throated Sparrow 72 58 Yellow-rumped Warbler 63 40 Magnolia Warbler 55 46 Palm Warbler 55 46 Northern Parula 47 35 Savannah Sparrow 44 40 Lincoln's/Swamp Sparrow 38 30 Unidentified Warbler 38 38 Black-and-White Warbler 37 32 Unidentified Sparrow 34 29 Swainson's Thrush 34 20 Black-throated Green Warbler 25 25 Ovenbird 25 22 Blackpoll Warbler 19 17 Unidentified Songbird 17 17 Black-throated Blue Warbler 16 12 Unidentified Warbler Genus Setophaga 16 16 Chestnut-sided Warbler 13 9 American Redstart 10 7 Nashville Warbler 10 7 Chipping Sparrow 6 5 Bay-breasted Warbler 5 4 Blackburnian Warbler 3 2 Dark-eyed Junco 3 2 Pine Warbler 2 2 Prairie Warbler 2 1 Solitary Sandpiper 2 1 Song Sparrow 2 1 Bobolink 1 1 Brown Thrasher 1 1 Cape May Warbler 1 1 Hermit Thrush 1 1 Mourning Warbler 1 1 Rose-breasted Grosbeak 1 1 Wilson's Warbler 1 1 Total 817 669
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