1. Bianchi N, Ancora S, Fazio ND, Leonzi C (2008) Cadmium, lead, and mercury levels in feathers of small passerine birds: noninvasive sampling strategy. Environ Toxicol Chem 27:2064–2070
2. Burger J, Gochfeld M, Jeitner C, Snigaroff D, Snigaroff R, Stamm T, Volz C (2008) Assessment of metals in down feathers of female common eiders and their eggs from the Aleutians: arsenic, cadmium, chromium, lead, manganese, mercury, and selenium. Environ Monit Assess 143:247–256
3. Eagles-Smith CA, Ackerman JT, Yee J, Adelsbach TL (2009) Mercury demethylation in waterbird livers: dose—response thresholds and differences among species. Environ Toxicol Chem 28:557–568
4. IAEA (1987) Intercalibration of analytical methods on marine environmental samples. Trace element measurements on fish homogenate. Results of the Worldwide 130 Intercomparison Run MA-B-3/TM Report 36. IAEA, Monaco
5. INEGI (2011) Mapas de climas. http://mapserver.inegi.org.mx/geografia/espanol/estados/sin/clim.cfmc=444&e=05 . Accessed 9 June 2011