Two dwellings were make on field in the ecological reserve El Plomito, municipality of Pitiquito, Sonora, Mexico. The first one during August - September 1997 and second one during July - August 1998. The samples were make with transect and tramp checkered ( grave tramps ). Five species of amphibians were identificated and also 26 species of reptiles. Relative density of these species were evaluate through census by indirect counting and was determinate that the species more abundant are: Bufo alvarius; Bufo punctatus, Callisaurus draconoides; Uta stansburiana; Cnemidophorus tigris; Heloderma suspectum; Dipsosaurus dorsalis; Crotalus tigris; Crotalus atratrox; Crotalus molossus; Masticophis lateralis; Masticophis flagellum; Gopherus agassizi.
It is considerate basing by observation and abundance that the population of these amphibians and reptiles species in the ecological reserve El Plomito are stable. If any dramatic modification in this area does not exist, the population will be assurance.

List of the species
1. Arizona elegans
2. Bufo alvarius
3. Bufo punctatus
4. Bufo retiformis
5. Callisaurus draconoides
6. Cnemidophorus burti
7. Cnemidophorus tigris
8. Coleonyx variegatus
9. Crotalus atrox
10. Crotalus cerastes
11. Crotalus molossus
12. Crotalus tigris
13. Crotaphytus collaris
14. Chionactis occipitalis
15. Dipsosaurus dorsalis
16. Gopherus agazzisi
17. Heloderma suspectum
18. Hypsiglena torquata
19. Lichanura trivirgata
20. Masticophis flagellum
21. Masticophis lateralis
22. Phrynosoma solare
23. Pternohyla fodiens
24. Sauromalus obesus
25. Scaphiopus couchi
26. Sceloporus clarkii
27. Sceloporus magister
28. Sonora semiannulata
29. Trimorphodon biscutattus
30. Urosaurus graciosus
31. Uta stansburiana