OK, here's what you guys have so far...
# collected...rank...species
7353...1st
3027...2nd
2238...3rd
2040...4th
1884...5th
1594...6th
1514...7th...Fowler's Toad (1st toad)
1443...8th...Dwarf American Toad
1398...9th
1346...10th
1249...11th
1148...12th
982...13th
979...14th...Spotted Salamander
964...15th
963...16th
963...17th
940...18th
917...19th
914...20th
---
705...26th...Spring Peeper
---
604...29th...Midland Watersnake
---
597...30th...Prairie Racerunner
590...31st...Copperhead (1st venomous snake)
---
543...36th...North American Racer
---
506...39th...Gray Treefrog *
---
418...47th...Three-toed Box Turtle
---
286...58th...Rough Earthsnake
---
265...60th...Eastern Gartersnake
---
124...78th...Red-bellied Snake
---
101...82nd...Timber Rattlesnake
* If you consider H. versicolor / chrysoscelis together, rank would be 29th.
So far, you guys have only 3 in the top 20. There are NO SNAKES OR TURTLES in the top 20, as the next hint. (Though the most collected snake species comes in at 21st.) The only firsts of any major groupings hit so far were 1st toad and 1st venomous snake.
Keep trying, if you like. I'll fill it in as people guess.