Date post: | 17-Dec-2015 |
Category: |
Documents |
Upload: | jordan-walton |
View: | 216 times |
Download: | 0 times |
HABITAT, NUTRITION, AND MERCURY IN
WATERBIRDS: PTILOCHRONOLOGY AS A
NOVEL BIOINDICATOR TOOL
Charles ClarksonHarbor Herons Meeting
Staten Island, NY13 January, 2011
Photo: Gerald Frost
OBJECTIVES
• Use ptilochronology (feather growth) to predict measures of parental quality, diet, and mercury burden in mixed species waterbird colonies at two locations along the east coast and demonstrate its worth as a universal bioindicator tool in avian studies.
Ptilochronology• Technique of measuring
feather growth– Growth-bars laid down in 24 hr
increments– Correspond directly with
nutritional condition of the individual
– Never used as a tool for bioindication
PREDICTIONS
• 1)Intraspecific variation in feather growth-bar width within a colony site will be indicative of variation in parental investment, as “higher quality” adults will provision nestlings more efficiently.
• 2)Intraspecific variation in feather growth-bar width between multiple colony sites will be indicative of differing habitat qualities (quality/quantity of diet, contaminant load).
METHODS: STUDY SPECIES• Two species belonging to the same
waterbird guild yet representing two endpoints of foraging habit. – Glossy Ibis (Plegadis falcinellus)
• Tactile forager• Invertebrates and mollusks• Foraging habit delimits spatial exploitation
– Double-crested Cormorant (Phalacrocorax auritus)• Habitat generalist• Free-swimming• Piscivorous
Photos: Gerald Frost
Future Directions• Model growth-bar width as a
predictor variable: Akaike’s Information Criterion• AICc = N*ln(SS/N)+2K+(2K(K+1))/(N-K-1)
• Captive food supplementation study• National Zoo, Washington D.C
• White-faced Ibis (Plegadis chihi)
• Scarlet Ibis (Eudocimus ruber)
• Colony-wide biomass consumption• How much biomass is
consumed during the breeding season?
• All nesting species (~8 spp)