Forty captive Mallards (Anas platyrhynchos), of both sexes, were separated into five groups and dosed with lead shot via oral intubation; one group was used as a control. Lead dosage differed in terms of shot number and size, as well as administration time. One hundred and thirty-five wild mallards were trapped between 1998 and 2001 in the Boada and Nava lagoons near the Canal de Castilla, in the Spanish province of Palencia. Radiologic techniques (ventrodorsal and lateral views) were used to detect lead shot in the gizzard and to determine degradation in dosed birds over time. Heparinized blood samples were taken from wild and captive mallards and blood lead levels were determined using anodic stripping voltammetry with a dropping mercury electrode. Clinical signs, injuries, and body weight were recorded. In approximately 90% of the experimentally dosed mallards, administered shot stayed in their gizzard until it degraded; this took approximately 30 days. Peak lead levels in blood were observed between days 10 and 20, and 10 days following a repeat dosage; males were more sensitive than females to a repeat dosage. During the experimental phase, 34% of birds died, and those that survived had varying degrees of anorexia, lethargy, and a decreased response to external stimulus. Of 135 tested wild mallards, 41% had a blood lead concentration higher than 0.200 μg/g. Lead shot was found embedded in 3.6% of the wild birds and 1.2% had a lead shot pellet in their gizzard.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 46 • No. 3