| dc.description.abstract | Addled Eggs from the endangered Northern Aplomado falcon (Falco femoralis septentrionalis) were collected annually during 2004-2017, from Laguna Atascosa National Wildlife Refuge and Matagorda Island in south Texas. Eggs were analyzed for persistent organic pollutants, including PCBs, PBDEs, and organochlorine pesticides. Eggshells were measured to determine thickness and to correlate with p,p’-DDE concentrations. My hypothesis is that environmental contaminants in Aplomado falcon eggs have decreased significantly over time and that eggshell thickness values are near pre-DDT measurements. Sixty egg homogenates were extracted, cleaned- up, and analyzed by gas chromatography-mass spectrometry. Eggshell thickness of 156 shells was measured three times around the equator with a Starrett micrometer. Eggshell thickness ranged from 0.206 mm to a maximum of 0.320 mm.
Decreasing eggshell thickness is correlated with increasing p,p’-DDE concentrations. The last reported contaminant concentrations in eggs of Aplomado falcons from south Texas were from 1999 to 2003, with a mean of 821 ng/g ww for p,p’-DDE and 1228 ng/g ww for total PCBs. Current contaminant values for this study show an average of 380 ng/g ww for p,p’- DDE, 368 ng/g ww for PCBs and 13 ng/g ww for PBDEs. This study provides information needed in support of the recovery of the Aplomado falcon in south Texas; populations had been steady at over 30 breeding pairs since 2011, however pairs dropped to 26 in 2018 following Hurricane Harvey. Overall, it appears that contaminant concentrations are low, at levels not likely to impact the recovery of the species. | en |
