The use of feathers in monitoring bioaccumulation of metals and metalloids in the South African endangered African grass-owl (Tyto capensis)
Abstract
Few studies have quantified metals in South
African species and no published data on residues specifically
in South African owl feathers exist. Tyto capensis is
listed as vulnerable within South Africa, making it preferable
to use a non-invasive technique to determine metal
bioaccumulation for this species. Comparisons are made
with the cosmopolitan T. alba to determine whether this
species could be used as a surrogate. Concentrations of
various metals were thus determined in feathers of the two
species and compared with liver and muscle samples.
Samples were taken from 119 owls collected as road kill
along a national road. A comparison of concentrations in
feathers revealed similarly higher concentrations of aluminium,
antimony, lead, nickel, and strontium, whereas
concentrations of chromium, copper, iron, manganese,
selenium, titanium and zinc were similarly higher in
internal tissues for both species. Metal concentrations of
owls were comparable to those reported in literature and
below toxic levels, suggesting that these metals were not
likely to impact the owls. Further regressions between
feathers and corresponding livers were examined to
determine if feathers were indicative of internal metal
burdens. Significant positive relationships were found for
aluminium, copper, lead, nickel and vanadium in T. alba
and nickel, manganese and vanadium in T. capensis.
Preliminary results support the feasibility of using feathers
as non-destructive indicators of environmental contamination
in T. capensis although caution needs to be taken when
interpreting the results.