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ATU F N RA O L T R N E E S M O T U STATE OF MICHIGAN R R C A P DNR E E S D MI N DEPARTMENT OF NATURAL RESOURCES CHIG A JENNIFER M. GRANHOLM LANSING REBECCA A. HUMPHRIES GOVERNOR DIRECTOR Michigan Frog and Toad Survey 2009 Data Summary There were 759 unique sites surveyed in Zone 1, 218 in Zone 2, 20 in Zone 3, and 100 in Zone 4, for a total of 1097 sites statewide. This is a slight decrease from the number of sites statewide surveyed last year. Zone 3 (the eastern half of the Upper Peninsula) is significantly declining in routes. Recruiting in that area has become necessary. A few of the species (i.e. Fowler’s toad, Blanchard’s cricket frog, and mink frog) have ranges that include only a portion of the state. As was done in previous years, only data from those sites within the native range of those species were used in analyses. A calling index of abundance of 0, 1, 2, or 3 (less abundant to more abundant) is assigned for each species at each site. Calling indices were averaged for a particular species for each zone (Tables 1-4). This will vary widely and cannot be considered a good estimate of abundance. Calling varies greatly with weather conditions. Calling indices will also vary between observers. Results from the evaluation of methods and data quality showed that volunteers were very reliable in their abilities to identify species by their calls, but there was variability in abundance estimation (Genet and Sargent 2003). Calling Indices of abundance will be reported as in past summaries but not used to actually estimate abundance of species. In April 2009, revisions to the Michigan endangered species list were finalized and published. The Blanchard’s cricket frog was listed as state threatened. Previously this species has been considered “special concern” which provided no legal protection except as provided in the Director’s Order regulating take on reptiles and amphibians. Now the species is legally protected from harm as defined in Part 365 of PA 451, Michigan Natural Resources and Environmental Protection Act. This protection includes fines for violators. Fowler’s toads were non existant in this year’s survey. This is a concern and efforts to investigate Fowler’s toad populations will be made next year. Mink frog observations continue to be low. There is a concern that data is not representative of the actual population due to the difficulty of surveying for this species. They tend to call at very early hours of the morning. There are still thoughts among the scientific community that mink frogs are actually declining in Michigan (J. Harding, pers. comm.). Pickerel frog occurrence remains low, possibly a result of confusion between this species’ calls and that of the Northern leopard frog. Pickerel frog occurrences have been known to be lower than the leopard frog in other Great Lakes states. Northern leopard frog observations continue to increase. Occurrences of the Cope’s gray treefrog continue to be low, relative to the Eastern gray treefrog. There is speculation that the continued NATURAL RESOURCES COMMISSION Keith J. Charters, Chair ● Mary Brown ● Hurley J. Coleman, Jr. ● John Madigan ● Timothy L. Nichols ● J. R. Richardson ● Frank Wheatlake STEVENS T. MASON BUILDING ● P.O. BOX 30028 ● LANSING, MICHIGAN 48909-7528 www.michigan.gov/dnr ● (517) 373-2329 Great Lakes, Great Times, Great Outdoors! decline in observations of Cope’s gray treefrogs may be due to the need to verify the observation. Surveyors may not be able to verify the call or may just not want to bother doing it. Data on wood frog observations should be interpreted cautiously due to their brief calling periods and associated difficulty of conducting the first run when wood frogs are calling. Green frog observations continue to show larger annual increases and decreases than other species. Reasons for this bouncing pattern are unknown at this time. Using all the routes that submitted data in 2009 the percentage of sites at which a species was heard per route was calculated for each zone (Tables 1-4). A statewide, 14-year analysis was done this year. The average number of sites per route at which a species was heard for all the routes was charted by year for each species. Trends were calculated for each species using the number of sites per route rather than changes in this factor as in the past. Negative trend numbers indicate a decline and vice versa. For most species the trends are similar between zones. Most species’ trends appear to be stable (Table 5). It is apparent, from statistical confidences (not presented in this report), that the number of years of data may still be inadequate to accurately assess populations of frogs and toads in Michigan, but research projects focusing on these populations are welcome and necessary. Table 1. 2009 SUMMARY OF FROG AND TOAD SURVEY Zone 1 - 759 sites Fowler’s Wood W. Spring Northern Pickerel American Gray **Cope’s **Blanchard’s Mink Green Bullfrog Toad Frog Chorus Peeper Leopard Frog Toad Treefrog Gray Cricket Frog Frog n=759 n=301ƒ n=759 Frog n=759 Frog n=759 n=759 n=759 Treefrog Frog n=0ƒ n=759 n=759 n=759 n=759 n=659ƒ Mean* 0 1.82 1.65 2.15 1.27 1.25 1.66 1.90 1.1 1.71 0 1.40 2.88 No. 0 259 389 619 157 7 314 526 10 5 0 478 146 Sites % 0 34.1 51.2 81.6 20.7 0.9 41.3 69.3 1.3 0.8 0 63.0 19.2 Sites * Mean calling index of sites where species were heard ƒ n is the number of sites within that species range - calculations include sites in native range of species only ** Confirmed observations Table 2. 2009 SUMMARY OF FROG AND TOAD SURVEY Zone 2 - 218 sites Fowler’s Wood W. Chorus Spring Northern Pickerel American Gray **Cope’s Blanchard’s Mink Green Bullfrog Toad Frog Frog Peeper Leopard Frog Toad Treefrog Gray Cricket Frog Frog n=218 n=120ƒ n=218 n=218 n=218 Frog n=218 n=218 n=218 Treefrog Frog n=0ƒ n=218 n=218 n=218 n=0ƒ Mean* 0 2.04 1.66 2.28 1.40 1.00 1.42 1.85 0 0 0 1.23 0 No. 0 87 72 191 23 2 59 122 0 0 0 107 0 Sites % Sites 0 39.9 33.0 87.6 10.6 0.9 27.1 56.0 0 0 0 49.1 0 * Mean calling index of sites where species were heard ƒ n is the number of sites within that species range - calculations include sites in native range of species only ** Confirmed observations Table 3. 2009 SUMMARY OF FROG AND TOAD SURVEY Zone 3 -20 sites Fowler’s Wood W. Chorus Spring Northern Pickerel American Gray **Cope’s Blanchard’s Mink Green Bullfrog Toad Frog Frog Peeper Leopard Frog Toad Treefrog Gray Cricket Frog Frog n=20 n=0ƒ n=20 n=20 n=20 Frog n=20 n=20 n=20 Treefrog Frog n=20ƒ n=20 n=20 n=20 n=0ƒ ---- 2.0 0 2.08 0 0 1.2 1.58 0 ---- 1.0 2.3 0 Mean* No. ---- 1 0 16 0 0 8 10 0 ---- 2 13 0 Sites % Sites ---- 5.0 0 80.0 0 0 40.0 50.0 0 ---- 10.0 65.0 0 Mean calling index of sites where species were heard ƒ n is the number of sites within that species range - calculations include sites in native range of species only ** Confirmed observations Table 4. 2009 SUMMARY OF FROG AND TOAD SURVEY Zone 4 - 100 sites Fowler’s Wood W. Chorus Spring Northern Pickerel American Gray **Cope’s Blanchard’s Mink Green Bullfrog Toad Frog Frog Peeper Leopard Frog Toad Treefrog Gray Cricket Frog Frog n=100 n=0ƒ n=100 n=100 n=100 Frog n=100 n=100 n=100 Treefrog Frog n=100ƒ n=100 n=100 n=100 n=0ƒ ---- 1.70 1.14 2.14 1.15 0 1.70 2.04 0 ------ 1.0 1.28 0 Mean* No. ---- 37 27 91 13 0 39 57 0 ------ 3 53 0 Sites % Sites ---- 37.0 27.0 91.0 13.0 0 39.0 57.0 0 ------ 3.0 53.0 0 * Mean calling index of sites where species were heard ƒ n is the number of sites within that species range - calculations include sites in native range of species only ** Confirmed observations Table 5. Trends of Michigan Frogs & Toads 1996-2009 SPECIES MEAN TREND (no. sites/route) WOODFR 3.6 3.4 WESTCF 4.4 4.9 SPRIPE 8.5 9.2 NORTLF 1.4 1.2 PICKFR 0.1 0.1 AMERTO 4.0 4.3 GRAYTR 6.7 7.8 FOWLTO 0.2 0.5 COPEGT 0.1 0.3 BLANCF 0.1 0.1 MINKFR 0.1 -0.1 GREFRO 5.7 6.3 BULLFR 1.1 1.4 All updated data summaries, phenologies, range maps and other information on the Michigan Frog and Toad Survey are featured on the DNR web site: http://www.michigan.gov/dnr/. Click on “Wildlife and Habitat” then “Research Projects” then “Frog and Toad Survey”. All questions concerning these data summaries and/or the Michigan Frog and Toad Survey should be directed to: Lori Sargent DNR - Wildlife Division P.O. Box 30180 Lansing, MI 48909 (517) 373-9418 e-mail: [email protected] Literature Cited Genet, K and L.G.