John/Chris, I totally agree that point counts from birding could misrepresent bird populations. I have been out on two different days and have seen big differences. I have a walk I take in the evening to listen to the thrushes. One evening I had 5 wood thrushes and 1 hermit thrush singing. The next night I had 3 hermit thrushes and 1 wood thrush. If you were doing a survey your numbers would depend on which night you chose. In Broome Co we don't have as much farming as John does and his comments on the large scale agriculture and the destruction of habitat on farms would make a big difference locally. Anyway, what do you make of this banding dataset from Canada? https://www.bsc-eoc.org/birdmon/default/popindices.jsp
I look at Long Point Bird Observatory since it seems to have the longest record. It seems that most species are doing very well on this long term dataset. It is interesting to note an increase in the 1970s for most species. Is this artificial? or real? I know the climate of the 60s and 70s was very chilly and springs were often cold and wet then it warmed in the 80s and 90s especially. But I don't understand how they calculate their population index. I assume it is normalized to the man-hours of banding. But what happening in the 1970s? Why such increases? From 2006-2016 most birds seems fairly stable based on their population index. Anyway, what are your thoughts on this? I am curious. Also there was a study on breeding bird survey data and they found that some of the data is contaminated by observers who, through normal aging, lose hearing. This was especially true of certain species that have higher pitch songs. So BBS may not be totally reliable either. Is anyone doing a study on total radar returns during migration? Theoretically, spring and fall migration could be quantified by integrating all the radar returns at night. I know there was a study done many years ago which used the old NWS radar system and compared the 1960s to the 1990s and they found a significant decrease in birds coming across the Gulf. But, I caution that radar operators could adjust the gain on the radar from site to site which would in turn, affect the returns so there could be some human caused inconsistencies in this dataset. Plus the 1974C radars came out which were less sensitive than the 1957S band radars. I wonder if this caused the decrease or contaminated the data for this study. Our latest radar system from the 1990s to present, you can't adjust the gain and they are all the same wavelength - 10 cm, so it is consistent. The resolution has gotten much better in the last 15 years so that could be a source of error if one looked at the 1990s and compared it to today. But at least over the last 10-15 years I believe one could quantify all radar returns which would give a macroscale look at nocturnal migration and monitor trends. Boy would I love to have time to do this!! I have 6 years to go until retirement.... Maybe someday I can work on this... Anyway, just some thoughts. Thanks John and Chris for your insights! Best, Dave On Tue, Jun 25, 2019 at 8:43 AM <k...@empacc.net> wrote: > Dave, Chris > > I believe one has to look further than two years and at efforts that use > the same methodology and criteria over long time periods for an accurate > estimate. The American Bird Conservancy and the Bird Banding Laboratory are > perhaps the best sources as are some of the long term banding studies > documented in journals such as North American Bird Bander. > > Regardless of cause it is to be expected that there will be some pockets > of plenty. > > The causes I believe are multiple, cumulative and you mention some. > Habitat loss and obstructions have increased dramatically and quickly in > the last two decades. Locally a very large negative is the growing dairy > agribusinesses that are converting pasture and hedgerows to large swaths of > sterile, monocropped land. Beyond this area chickens and hogs are being > raised with the same methods and habitat loss. South and Central America > habitat loss has also been on the rise. > > Yes a few species have been documented to have cyclical ups and downs. A > few may also be subject to WNV and I believe Anne would have better data on > that than I. > > Any counts that are aperiodic could well be the result of the cyclic > nature of weather, blocking fronts, timing during migrations, observer bias > and more. > > Insect populations are indeed crashing and the 'Have you see any bugs on > your windshield?" type articles have increased awareness, but the loss has > not been adequately studied. The combination of all this has greatly > decreased habitat and food sources at the lower end of the life web. > > In any event I do not believe we can rely on birder reports for meaningful > data but should rather look to long term studies with timing and protocols > that are standard year to year. > > Thanks for your input. > John > --- > John and Sue Gregoire > Field Ornithologists > Kestrel Haven Migration Observatory > 5373 Fitzgerald Rd > Burdett, NY 14818 > 42.443508000, -76.758202000 > "Create and Conserve Habitat" > > On 2019-06-23 20:13, David Nicosia wrote: > > Chris, > > Fortunately, I have found the opposite for the most part.... > > I did two trips this past week one to Triangle State Forest and Hawkins > Pond State Forest in Broome County and neotropical migrants were quite > common especially Red-Eyed Vireos, Ovenbirds. > > see: Triangle State Forest: https://ebird.org/view/checklist/S57456491 > Most of the warblers were found in a small stretch of about 1 mile in the > spruce, hemlock, pine, northern hardwood forests. > > and Hawkins Pond State Forest: https://ebird.org/view/checklist/S57564971 > Most of the birds were in the stretch of spruce, hemlock, pine and maple, > oak about 1.5 miles. > > I lost count of ovenbirds at Hawkins! Red-eyed vireos were all over. > Blackburnian warblers too were the most I have had at this location. Now > this is just my observations in one county. > > In the western Adirondacks, at Star Lake, Red-Eyed Vireos seemed > everywhere along with ovenbirds. Blackburnian warblers were quite common > too. > > see: https://ebird.org/view/checklist/S57189909 for my Star lake walk. > > In my yard, there also seems to be more bird activity this year. I have at > least 2 maybe 3 pairs of Gray Catbirds this year vs just one pair most > years. I also have 2 pairs of red-eyed vireos vs one pair or in some years > none! > > Anyway, what is the cause of the drastic declines that you are observing? > That is the bigger question. Could it be disease? Does west nile virus > kill songbirds? Have insect populations crashed? Habitat loss, increase > in towers, wind farms etc are happening gradually so the declines should be > slow. Or maybe there is a natural cycle and some areas are seeing the > minimum in numbers which is lower than any other minimum in the past? > > Concerned too (but optimistic), > Dave > > > > > > > > > > > > > > > > On Sat, Jun 22, 2019 at 9:01 PM Christopher T. Tessaglia-Hymes < > c...@cornell.edu> wrote: > >> Good evening, >> >> This morning I was joined by Bartels Science Illustrator, Jessica French, >> for a birding trip to Hammond Hill State Forest. It was disconcertingly >> quiet up there. I probably should not have had such high expectations, >> given how quiet this spring has been (a handful of very quiet trips to the >> Hawthorn Orchard) and how few night flight calls were recorded over our >> house in Etna. I'm still analyzing my night flight call data, but those >> data from May 3 through May 24 are concerning, to say the least. I have >> also read postings from VINS and notable Bicknell's Thrush researcher, >> Chris Rimmer, making similar observations about his Mount Mansfield, VT, >> field site this spring ("disquietingly low" vocal activity and mist net >> captures). >> >> Here are two checklists completed from our two, approximate four-mile, >> bushwhack walks this morning. Nice habitat. Few insects. Few birds. No >> ticks (but not complaining). >> >> Loop to SE of Star Stanton and Canaan Rd Intersection: >> >> https://ebird.org/view/checklist/S57605395 >> >> Notably absent or low numbers of birds -- >> Barred Owl >> Red-bellied Woodpecker >> Pileated Woodpecker >> Least Flycatcher >> Great Crested Flycatcher >> Red-eyed Vireo (very low numbers) >> Winter Wren >> Wood Thrush >> Baltimore Oriole >> Mourning Warbler >> Hooded Warbler >> American Redstart >> Chestnut-sided Warbler >> Black-throated Blue Warbler >> Black-throated Green Warbler >> Canada Warbler >> Scarlet Tanager (very low numbers) >> Rose-breasted Grosbeak >> >> Loop between Hammond Hill and Canaan Rd: >> >> https://ebird.org/view/checklist/S57605776 >> >> Notably absent or low numbers of birds -- >> Barred Owl >> Red-bellied Woodpecker >> Pileated Woodpecker >> Least Flycatcher >> Great Crested Flycatcher >> Red-eyed Vireo (very low numbers) >> Winter Wren >> Wood Thrush >> Baltimore Oriole >> Mourning Warbler >> Hooded Warbler >> American Redstart >> Chestnut-sided Warbler >> Black-throated Blue Warbler >> Black-throated Green Warbler >> Canada Warbler >> Scarlet Tanager (very low numbers) >> Rose-breasted Grosbeak >> >> Concerned, >> Chris T-H >> >> -- >> Chris Tessaglia-Hymes >> PO Box 488 >> 8 Etna Lane >> Etna, NY 13062 >> 607-351-5740 >> -- >> *NYSbirds-L List Info:* >> Welcome and Basics <http://www.northeastbirding.com/NYSbirdsWELCOME.htm> >> Rules and Information <http://www.northeastbirding.com/NYSbirdsRULES.htm> >> Subscribe, Configuration and Leave >> <http://www.northeastbirding.com/NYSbirdsSubscribeConfigurationLeave.htm> >> *Archives:* >> The Mail Archive >> <http://www.mail-archive.com/nysbirds-l@cornell.edu/maillist.html> >> Surfbirds <http://www.surfbirds.com/birdingmail/Group/NYSBirds-L> >> ABA <http://birding.aba.org/maillist/NY01> >> *Please submit your observations to **eBird* >> <http://ebird.org/content/ebird/>*!* >> -- >> > -- > *Cayugabirds-L List Info:* > Welcome and Basics <http://www.northeastbirding.com/CayugabirdsWELCOME> > Rules and Information <http://www.northeastbirding.com/CayugabirdsRULES> > Subscribe, Configuration and Leave > <http://www.northeastbirding.com/CayugabirdsSubscribeConfigurationLeave.htm> > *Archives:* > The Mail Archive > <http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html> > Surfbirds <http://www.surfbirds.com/birdingmail/Group/Cayugabirds> > BirdingOnThe.Net <http://birdingonthe.net/mailinglists/CAYU.html> > *Please submit your observations to eBird > <http://ebird.org/content/ebird/>!* > -- > > -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
