Dietary mercury exposure causes decreased escape takeoff flight performance and increased molt rate in European starlings (Sturnus vulgaris)
- 322 Downloads
Mercury is a widespread and persistent environmental contaminant that occurs in aquatic and terrestrial habitats. Recently, songbirds that forage from primarily terrestrial sources have shown evidence of bioaccumulation of mercury, but little research has assessed the effects of mercury on their health and fitness. There are many indications that mercury negatively affects neurological functioning, bioenergetics, and behavior through a variety of mechanisms and in a wide array of avian taxa. Effective flight is crucial to avian fitness and feather molt is an energetically expensive life history trait. Therefore, we investigated whether mercury exposure influenced flight performance and molt in a common songbird, the European starling (Sturnus vulgaris). Specifically, we dosed the diet of captive starlings with methylmercury cysteine at 0.0, 0.75, or 1.5 μg/g wet weight and recorded changes in flight performance after 1 year of dietary mercury exposure. We also recorded the annual molt of wing feathers. We found that individuals dosed with mercury exhibited decreased escape takeoff flight performance compared with controls and blood mercury was also correlated with an increased rate of molt, which can reduce flight performance and thermoregulatory ability. This study reveals two novel endpoints, flight performance and molt, that may be affected by dietary mercury exposure. These findings suggest a potential impact on wild songbirds exposed to mercury levels comparable to the high dosage levels in the present study. Any decrease in flight efficiency could reduce fitness due to a direct impact on survival during predation events or by decreased efficiency in other critical activities (such as foraging or migration) that require efficient flight.
KeywordsFlight Mercury Molt Sub-lethal effects European starling
This study was funded by E.I. DuPont de Nemours and Company and research was completed with oversight from the South River Science Team, which is a collaboration of state and federal agencies, academic institutions, and environmental interests. This study was also supported by NSF award IOS-1257590. The College of William and Mary provided additional funds. Thank you to Margaret Whitney for dose preparation and analyses. Special thanks S. Laurie Sanderson for advice and to all the graduate and undergraduate researchers who assisted in developing and carrying out this project.
Conflict of interest
The authors declare that they have no conflict of interest.
- Cai Y, Liu G, O’Driscoll N (2011) Environmental chemistry and toxicology of mercury. Wiley, HobokenGoogle Scholar
- Cambier S, Benard G, Mesmer-Dudons N, Gonzalez P, Rossignol R, Brethes D, Bourdineaud JP (2009) At environmental doses, dietary methylmercury inhibits mitochondrial energy metabolism in skeletal muscles of the zebra fish (Danio rerio). Int J Biochem Cell Biol 41:791–799. doi: 10.1016/j.biocel.2008.08.008 CrossRefGoogle Scholar
- Evers DC, Savoy LJ, DeSorbo CR, Yates DE, Hanson W, Taylor KM, Siegel LS, Cooley JH Jr, Bank MS, Major A, Munney K, Mower BF, Vogel HS, Schoch N, Pokras M, Goodale MW, Fair J (2008) Adverse effects from environmental mercury loads on breeding common loons. Ecotoxicology 17:69–81. doi: 10.1007/s10646-007-0168-7 CrossRefGoogle Scholar
- Ginn HB, Melville DS (1983) Moult in birds. British Trust for Ornithology, NorfolkGoogle Scholar
- Glaser V, Leipnitz G, Straliotto MR, Oliveira J, dos Santos VV, Duval Wannmacher CM, de Bern AF, Teixeira Rocha JB, Farina M, Latini A (2010) Oxidative stress-mediated inhibition of brain creatine kinase activity by methylmercury. Neurotoxicology 31:454–460. doi: 10.1016/j.neuro.2010.05.012 CrossRefGoogle Scholar
- Heath JA, Frederick PC (2005) Relationships among mercury concentrations, hormones, and nesting effort of white ibises (Eudocimus albus) in the Florida everglades. Auk 122:255–267. doi: 10.1642/0004-8038(2005)122[0255:RAMCHA]2.0.CO;2
- Laties VG, Evans HL (1980) Methylmercury induced changes in operant discrimination by the pigeon. J Pharmacol Exp Ther 214:620–628Google Scholar
- Leblond VS, Hontela A (1999) Effects of in vitro exposures to cadmium, mercury, zinc, and 1-(2-chlorophenyl)-1-(4-chlorophenyl)-2,2-dichloroethane on steroidogenesis by dispersed interrenal cells of rainbow trout (Oncorhynchus mykiss). Toxicol Appl Pharm 157:16–22. doi: 10.1006/taap.1999.8660 CrossRefGoogle Scholar
- Lima SL (1993) Ecological and evolutionary perspectives on escape from predatory attack: a survey of North American birds. Wilson Bull 105:1–47Google Scholar
- Nocera JJ, Taylor PD (1998) In situ behavioral response of common loons associated with elevated mercury (Hg) exposure. Conserv Ecol [Ecology and Society] 2(2):10Google Scholar
- Olsen B, Evers DC, DeSorbo C (2000) Effect of methylated mercury on the diving frequency of the common loon. J Ecol Res 2:67–72Google Scholar
- Pyle P (1997) Identification guide to North American birds. Slate Creek Press, BolinasGoogle Scholar
- Ralph CJ, Geupel GR, Pyle P, Martin TE, DeSante DF (1993) Handbook of field methods for monitoring landbirds. General technical report PSW-GTR-144. Pacific Southwest Research Station, Forest Service, Department of Agriculture, Albany, CAGoogle Scholar