Presentation on theme: "Chris Butler. Yellow Rails are secretive, nocturnal birds that breed in the northern US and Canada and winter along the coast, from Texas to North Carolina."— Presentation transcript:
Yellow Rails are secretive, nocturnal birds that breed in the northern US and Canada and winter along the coast, from Texas to North Carolina Bookhout, T. A. 1995. Yellow Rail (Coturnicops noveboracensis). In The Birds of North America, No. 139 (A. Poole, and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists’ Union, Washington, D.C.
7 Mar 1842 ◦ First Yellow Rail collected 1950s – one record 1960s – one record 1970s – three records 1980s – no records 1990s – four records 21 st century – Arbour found Yellow Rails to be regular in extreme southeastern OK during autumn migration Heck, B. A. and W. D. Arbour. 2008. The Yellow Rail in Oklahoma. Bulletin of the Oklahoma Ornithological Society 41: 13-15.
Began banding Yellow Rails in Oklahoma in 2008 in order to ◦ 1.) Estimate population sizes ◦ 2.) Use stable isotopes to identify where these birds originated ◦ 3.) Examine age/sex ratios ◦ 4.) Examine fat deposition across months In 2009, began collaboration with Jennifer Wilson and Charles Brower at Texas mid-Coast NWR to compare OK and TX rails
Spotlight birds and then catch them with handheld nets
Birds were banded, aged according to Pyle (2008), scored for fat, and two rectrices (tail feathers) were removed for stable isotope analysis and genetic analysis Mark-recapture history analyzed using POPAN in program MARK Rectrices from MB were obtained with the aid of Kristen Martin and Derek Furutani, while SK feathers came from Kiel Drake
To date, more than 100 Yellow Rails have been banded at Red Slough WMA ◦ In addition, Yellow Rails have also been encountered at other locations in SE OK during mid-winter, including Grassy Slough (McCurtain Co.) and Hugo WMA (Choctaw Co) During 2009-10, 176 Yellow Rails were banded at San Bernard NWR, TX ◦ There were 17 recaptures during this time
DateNewRecaptures 10 Nov 200913 17 Nov 20095 28 Nov 20094 4 Jan 20101 5 Jan 20109 16 Jan 201025 2 Feb 2010143 7 Feb 2010142 13 Feb 2010251 1 Apr 2010153 8 Apr 201074 10 Apr 2010173 13 Apr 2010171 20 Apr 201010
Some of the birds that we banded in November were re-encountered as late as March, so we estimated the population size at Red Slough for late Nov 2009 – Mar 2010 POPAN estimate is 68 ± 18 individuals at Red Slough, 976 ± 234 Yellow Rails overwintered at San Bernard NWR At both locations, ~4 individuals/ha
Deuterium results for Oklahoma (n = 45) and TX (n = 21) suggest that rails in TX generally came from areas with a deuterium excess of -141 ± 5 while rails from Oklahoma came from areas with a deuterium excess of -131 ± 4 However, the differences were not significant (Mann-Whitney, p = 0.17)
We obtained DNA sexes from 92 individuals, 52 of which were male and 40 of which were female. The sex ratio for both locations combined was slightly male-biased (sign test, p = 0.038). However, there was not a significant difference in sex ratios between OK and TX (sign test, p = 0.5).
Of the birds captured during January through April, 133 out of 178 (74.7%) could not be assigned to a SY/ASY age class, as they showed a mixture of SY/ASY characteristics ◦ Instead, we compared the ratios of birds caught during November and December (i.e. we compared the ratio of HY:AHY birds). Seven of 19 birds (36.8%) captured at San Bernard NWR during this period were aged as HY, while six of 14 birds (42.9%) captured at Red Slough WMA during this period were aged as HY. The ratio of HY:AHY (after hatch-year) birds was not significantly different between the two locations (Fisher’s exact test, p =0.99).
Birds in Oklahoma maintained more fat reserves than birds in TX ◦ Out of 124 birds banded in TX, only 1(!) had fat, which was scored as a “1” (the lowest score)
The density of Yellow Rails (~4 rails / ha) wintering in southeastern Oklahoma is comparable to the density in San Bernard NWR ◦ However, drought during 2011/12 & 2012/13 greatly reduced the number encountered in OK. The SIA results suggest that birds wintering in OK & TX breed primarily on the Canadian prairies ◦ Many samples remain to be run ◦ Need to re-run samples from SK The sex ratio was slightly male-biased with approximately equal numbers of HY/AHY birds detected Birds in OK apparently store more fat during the winter than birds in TX
1.) Surveys to determine winter distribution and density of Yellow Rails should be undertaken ◦ If they overwinter in southeastern Oklahoma, where else may they occur? 2.) Winter habitat requirements should be determined ◦ Does habitat structure or species composition affect occupancy? What are the effects of various fire regimes? How does hydrology affect density? How may climate change affect this species? 3.) Extent of migratory connectivity in this species should be examined ◦ Where do birds breeding in the eastern portion of the range overwinter? ◦ What is the best way to track movements of this species?
Thanks to ◦ UCO’s Office of Research & Grants ◦ USDA Forest Service ◦ USFWS ◦ OSU Forest Resources Center, SW LA Refuge Complex, and MS Sandhill Crane NWR for providing accommodation ◦ David Eason, Katrina Hucks, Daniel Whalen, Nat Burgess, Eric and Erica Judd, Jill Stinedurf, Stephen Frazee, John Polo, Monte Stone, Erica Davis, Lisa Pham, Robert and Cameron Bastarache, Emily Stine, Craig Koenigs, Son Nguyen, Erica Becker, Chris Roy, David Arbour, Berlin Heck, Kim McBride, Jennifer Curtis, Shay Still, Jeremy Young, Bryan Wilcox, Brad Rising, Paul Bjornen, Gloria Caddell, the UCO Ornithology class of 2010 & 2012, Doug Wood and Dr. Wood’s ornithology class for assistance with fieldwork