Great tit response to decreasing industrial heavy metal emissions.

This study evaluated the effects of environmental pollution on decreasing great tit (Parus major) breeding parameters in an industrial area in the west coast of Portugal. Several great tit breeding parameters were monitored in the industrial area, as well as in a rural area not affected by industrial emissions. Low levels of air pollution in both industrial and rural areas were confirmed by assessing trace element concentrations in pine needles. Concentrations of Cd and Hg in pine needles from the industrial area (Cd = 0.05 ppm; Hg = 0.005 ppm) were significantly lower than those found in needles collected from the reference area (Cd = 0.07 ppm; Hg = 0.007 ppm). Additionally, the breeding success of great tits increased in the industrial area in comparison to the reference area (0.93 ± 0.08 and 0.62 ± 0.22, respectively). The changes on great tit breeding parameters were probably related with changes in the breeding density of other competitive species, together with a decreasing frass-fall biomass. Further long-term ecological studies in industrial areas are necessary to understand the changing breeding performance and strategies used by great tits in response to pollution shifts in the environment.

Persistent organic pollutants and inorganic elements in the Balearic shearwater Puffinus mauretanicus wintering off Portugal.

This study presents the first data on trace element and organic pollutant concentrations in the Critically Endangered Balearic shearwater Puffinus mauretanicus collected in 2010 and 2011 in Portugal. Trace element levels were below the threshold levels for adverse effects on birds, despite the Hg concentrations in feathers (4.35µg·g-1ww). No significant differences were detected between individuals from 2010 and 2011 except for Se concentrations in liver, feathers and muscle (higher in 2010) and Ag in liver and muscle (higher in 2011). No significant differences were detected in total concentrations of organochlorine compounds in Balearic shearwaters between years, although PCB congeners -101 and -180 presented higher concentrations in individuals from 2010. The PCB congeners -138, -153 and -180, and 4.4-DDE were detected in all individuals. This study on toxic elements and organic pollutants in wintering Balearic shearwaters provides baseline data from which deviations can be detected in the future.

Use of skin and blubber tissues of small cetaceans to assess the trace element content of internal organs.

In order to evaluate the use of biopsy samples as non-destructive tool for assessing trace element concentrations in small cetaceans, the concentrations of 14 trace elements were determined in skin, blubber, liver and kidneys of four species of small cetaceans (i.e. common dolphin Delphinus delphis, harbour porpoise Phocoena phocoena, bottlenose dolphin Tursiops truncatus and striped dolphin Stenella coeruleolba), stranded and/or by-caught along the NE Atlantic Ocean coast between 2001 and 2008. Only Cu, Fe, Hg, Mn, Ni and Zn were above the detection limit of the instruments and showed recoveries satisfactory enough to be interpreted. Among these trace elements, Hg was the only one showing a significant correlation between concentrations in and those in liver and kidneys. In consequence skin and blubber can only be used as non-invasive monitoring tissues to investigate Hg bioaccumulation in internal tissues for cetacean populations.

Assessing heavy metal pollution using Great Tits (Parus major): feathers and excrements from nestlings and adults.

Passerine species have been increasingly used as bioindicators of metal bioaccumulation especially by taking benefit of non-invasive procedures, such as collecting feathers and excrements. In 2009, metal (As, Cd, Cu, Hg, Ni, Pb, Se and Zn) concentrations were determined in feathers and excrements of nestling and adult female great tits (Parus major) in industrial (a paper mill) and rural sites in maritime pine forests on the west coast of Portugal. The aim of this study was to compare the levels of metals between the areas but also between sampling methods (feather vs. excrement) and age classes (nestling vs. adult). Although excrements and feathers of nestling great tits showed different concentrations, similar patterns of accumulation were detected in both study areas. There was a significantly higher concentration of mercury in the industrial area and significantly higher concentrations of arsenic in the rural area in both sample types. Metal levels in adult females had quite different results when compared to nestlings, and only nickel presented significantly higher levels near the paper mill. Since metal levels showed a consistent pattern in feathers and excrements of nestling great tits, we conclude that both represent good and non-invasive methods for the evaluation of these elements in polluted areas.

Trace elements in faeces of great tit nestlings in relation to breeding performance in coastal areas in central Portugal.

This long-term study (2003-2010) compared the breeding parameters of great tits living in a paper-and-pulp-industry area to those of great tits living in a rural area on the west coast of Portugal. We also measured the abundance of caterpillar biomass, an important food source and determinant of breeding success for tits. In 2009, we further analysed trace metal [arsenic (As), calcium (Ca), cadmium, copper, mercury (Hg), nickel, lead, selenium, and zinc] as well as Ca concentrations in excrement of 15-day-old great tit nestlings. Generally, for most trace metals, fecal concentrations were similar at both sites. Nonetheless, greater Hg levels and lower As levels were detected in the industrial area. Great tits laid more eggs and produced more fledglings in the industrial area than in the rural area. Caterpillar biomass was also greater in the industrial area, which likely explains the better breeding success. Our results suggest that there are no direct effects of emissions on the studied species.

The use of passerine feathers to evaluate heavy metal pollution in Central Portugal.

In 2003, two sampling strategies were applied in order to evaluate metal contamination in passerine bird feathers. One strategy included the use of nest boxes and nestling great tits in a forest habitat (MU). The other strategy focused on the use of mist nets to capture adult blackbirds, robins and blackcaps in a fragmented non-forested habitat (EST). There was a significantly higher concentration of mercury in great tits (1.09 ± 0.40) sampled in MU and also in robins (3.44 ± 0.91) and blackcaps (1.62 ± 1.99) sampled in EST, in comparison to the reference site (0.66 ± 0.68; 2.04 ± 1.12; 0.32 ± 0.43; respectively). Concerning interspecific differences, robins accumulated significantly more metals than blackbirds or blackcaps.