ENDOCRINE EFFECTS OF THE HERBICIDE ...

ENDOCRINE EFFECTS OF THE HERBICIDE LINURON ON THE AMERICAN GOLDFINCH (CARDUELIS TRISTIS) (Efectos Endocrinos del Herbicida Linuron sobre Carduelis tristis) Author(s): KAREN M. SUGHRUE, MARGARET C. BRITTINGHAM, JOHN B. FRENCH JR. Reviewed work(s): Source: The Auk, Vol. 125, No. 2 (April 2008), pp. 411-419 Published by: University of California Press on behalf of the American Ornithologists' Union Stable URL: http://www.jstor.org/stable/10.1525/auk.2008.06264 . Accessed: 13/04/2012 18:44 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected].

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The Auk 125(2):411–419, 2008  The American Ornithologists’ Union, 2008�� . Printed in USA.

Endocrine Effects of the Herbicide Linuron on the American Goldfinch (Carduelis tristis ) K aren M. S ughrue ,1,2,3 M argaret C. B rit tingham ,1 2

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J ohn B. French , J r . 2

1 School of Forest Resources, Pennsylvania State University, Forest Resources Building, University Park, Pennsylvania 16802, USA; and U.S. Geological Survey, Patuxent Wildlife Research Center, Beltsville Lab, BARC-East 308, 10300 Baltimore Avenue, Beltsville, Maryland 20705, USA

Abstract.—�� Certain contaminants �� alter �� normal physiological �� function, �� morphology, �� and �� behavior �� of �� exposed �� organisms �� through �� an endocrine mechanism. We evaluated how the herbicide linuron, an endocrine-active compound, affects physiological parameters and secondary sex characteristics of the American Goldfinch (Carduelis tristis). When administered at relatively low doses (control, 1.0, 4.0, and 16.0 μg linuron per gram of body mass per day), linuron delayed prealternate molt progression in a dose-dependent manner. At the high dose level, linuron exposure lowered hematocrit and female plasma thyroxine concentrations and increased body mass. Neither plasma testosterone concentrations nor the color of plumage or integument of birds in the treatment groups were different from those of the control group. Overall, the physiological effects that were measured suggested disruption of thyroid function. These results highlight the importance of continual monitoring of avian populations for potential effects of exposure to pesticides and other chemicals at sublethal concentrations. Received 12 December 2006, accepted 19 July 2007. Key words: American Goldfinch, Carduelis tristis, endocrine disrupters, linuron, molt, thyroxine.

Efectos Endocrinos del Herbicida Linuron sobre Carduelis tristis Resumen.—�� Algunos contaminantes �� alteran �� la �� función �� fisiológica �� normal, la �� morfología ��y el �� comportamiento �� de los �� organismos �� expuestos a estos contaminantes a través de un mecanismo endocrino. Evaluamos la forma en que el herbicida Linuron, un compuesto endocrinamente activo, afecta los parámetros fisiológicos y los caracteres sexuales secundarios de Carduelis tristis. Al ser administrado en dosis relativamente bajas (control, 1.0, 4.0, y 16.0 μg de Linuron por gramo de masa corporal por día), el herbicida atrasó el desarrollo de la muda prealterna de una manera dependiente de la dosis. A una dosis alta, la exposición al Linuron bajó los niveles de hematocrito y las concentraciones plasmáticas de tiroxina en las hembras, y aumentó el peso corporal. Ni las concentraciones plasmáticas de testosterona ni la coloración del plumaje o integumento de las aves del grupo tratado fueron diferentes de las del grupo control. En general, los efectos fisiológicos que fueron medidos sugirieron una alteración en la función de la tiroides. Estos resultados resaltan la importancia de un monitoreo continuo de las poblaciones de aves para detectar efectos potenciales de la exposición a concentraciones subletales de pesticidas y otros químicos.

Concern about sublethal effects of pesticides has heightened in recent years, particularly with regard to compounds that can disrupt the normal function of the endocrine system (Short and Colborn 1999, Scanes and McNabb 2003). Over the past several decades, an extensive body of literature on the effects of these endocrine-active compounds (EACs) in wildlife has accumulated (Vos et al. 2000). Well-publicized field studies involving birds include documentation of dramatic population declines in raptors in the 1960s and 1970s because of eggshell thinning and of numerous immune and thyroid disorders in piscivorous birds within the Great Lakes region (for reviews, see Botham et al. 1999, Giesy et al. 2003).

Few avian studies pertaining to EACs have examined their potential effects on passerines. However, given their foraging habits, insectivorous and granivorous songbirds are likely to be exposed to potentially endocrine-active pesticides via either their diet or dermal exposure (Vyas 1999). Experimental work on passerines has shown that exposure to EACs can alter reproductive organs (Millam et al. 2002), and field evidence indicates that EACs can affect other endocrine-related functions such as the development of adult-type plumage (McCarty and Secord 2000). Effects observed in wild birds, such as changes in sex ratios and alterations in reproductive behavior, are hypothesized examples of

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Present address: U.S. Fish and Wildlife Service, 70 Commercial Street, Suite 300, Concord, New Hampshire 03301, USA. E-mail: [email protected]

The Auk, Vol. 125, Number 2, pages 411–419. ISSN 0004-8038, electronic �� ISSN�� 1938-4254.  2008 by The American Ornithologists’ Union. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Rights and Permissions website, http://www. ucpressjournals.com/reprintInfo.asp DOI: 10.1525/auk.2008.06264

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sex-hormone modulation (Giesy et al. 2003, Scanes and McNabb 2003). There is also evidence that EACs can alter avian thyroid function (Rolland 2000). Change in thyroid hormone concentrations could have numerous and varied effects during a bird’s life, because thyroid hormones are essential for normal growth (Scanes et al. 1984) and are involved in the regulation of key annual events, including molt (Payne 1972), migration (Pant and Chandola-Saklani 1993), and reproduction (Thapliyal 1969, Lothrop 1996). The purpose of the present study was to examine the effects of a known EAC on hormones (testosterone and thyroxine) and on the secondary sex characteristics of a common passerine species, the American Goldfinch (Carduelis tristis; hereafter “goldfinch”). The goldfinch has a seasonal change in bill color (orange bill with the alternate plumage and black bill with the basic plumage) that is affected by testosterone (Mundinger 1972); therefore, chemicals that affect androgen concentrations or function could alter this color change. In addition to reproductive hormones, thyroid hormones may also affect development of secondary sex characteristics through their promotion of growth of reproductive tissues and their role in molt and feather regrowth. Goldfinches have a carotenoid-based alternate plumage (McGraw et al. 2001), and there is evidence that pigment-based plumage coloration in avian species is influenced by hormones (Voitkevich 1966, Kimball 2006). Linuron is a phenylurea herbicide that is known to have antiandrogenic properties (Cook et al. 1993, Lambright et al. 2000) as well as antithyroid activity (Rehnberg et al. 1988) in rodents. It is commonly used in the United States and Canada to control broadleaf and grassy weeds, including Canada Thistle (Cirsium arve) (Caux et al. 1998, Short and Colborn 1999, VanGessel 1999). Its half-life in soils is highly variable (7 days to 18 months, depending on application rate and environmental factors; Caux et al. 1998), and it readily leaches through soils to pollute groundwater or contaminates surface water by way of agricultural runoff (U.S. Environmental Protection Agency [USEPA] 1988, Kookana et al. 1995). Given its use on a variety of crop and non-crop sites, chronic dietary exposure is likely for humans, livestock, and wildlife (Anfossi et al. 1993, Pasquini et al. 1994). Wild birds can be exposed to linuron and other herbicides during application (Freemark and Boutin 1995) or through ingestion in food or water. For example, linuron was one of several pesticides found in the adipose tissue of the Wild Turkey (Meleagris gallapavo; Bridges and Andrews 1977). Goldfinches may encounter linuron when foraging for thistle seeds, a preferred food item (Middleton 1993). M ethods We established a captive colony of wild-caught goldfinches (n = 56) in March 2003 and housed the birds in pairs in outdoor flight cages (3 × 3 × 16 m) at the U.S. Geological Survey Patuxent Wildlife Research Center, Laurel, Maryland (IACUC # 00R168). We divided male and female birds into four treatment groups (n = 14 per treatment group), but because we caught a greater number of males, there were five male–female pairs and two male–male pairs per group. We lined cages with tennis netting along the side and back walls, and each contained a nest box and natural vegetation for perches. The birds’ diet was composed of sunflower chips and niger seed with a vitamin supplement (Vionate vitamin-mineral


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powder, Omaha Vaccine, Omaha, Nebraska; 0.135 g per bird) added and mixed into the seeds with vegetable oil. We dissolved the coccidiostat sulfadimethoxine into the birds’ drinking water (Animal Health Sales, Selbyville, Delaware; 0.497 g per liter of water) to reduce coccidial (Isospora spp.) infections (Brawner et al. 2000). We established treatment doses (control, 1.0, 4.0, and 16.0 µg linuron per gram of body mass per day) and exposed the birds via the seed diet. We considered these doses to be of low toxicity to the birds, given that the highest dose is ~60× lower than the LC50 (lethal concentration for 50% of exposed population) for 17-weekold Northern Bobwhites (Colinus virginianus) (USEPA 1995). We dissolved linuron (Chem Service, West Chester, Pennsylvania) in ethanol before blending it into vegetable oil and then applied the treated oil to the seed in a large mixing bowl. We coated the control diet with oil only. We initiated treatment on 11 March 2003 and continued for the next four months. Before onset of treatment, during treatment, and approximately one and a half months after treatment, we collected blood samples and measured molt progression, bill color change, and body mass. Data were generally collected every three weeks. For molt progression, we used methods similar to those of previous studies (Billard and Humphrey 1972, Hipes and Hepp 1995). We collected molt data for body feathers only and scored molt in four regions (head, back, belly, and throat) on an ordinal scale. We examined each region for developing follicles and assigned a score based on molt intensity: 0 = no feathers molting, 1 = light stage of molt (50%). We added these rankings together for a total body-molt score (maximum score = 12). For progression of orange bill color, we monitored the transitional change from black to orange by measuring the amount of orange pigment (carotenoid) visible along the length of the bill using calipers (measured to 0.10 mm; Mundinger 1972). We used a UV-VIS S2000 spectrophotometer (Ocean Optics, Dunedin, Florida) to measure the color of plumage (back and breast regions) and integument (bill and foot) before onset of treatment and at the end of the study. To measure hormone concentrations (testosterone and thyroxine) and hematocrit, we collected ~120 µL of blood from the brachial vein in a hematocrit tube. We collected blood between 0800 and 1200 hours and kept the hematocrit tubes on ice. Immediately after blood collection, we centrifuged and stored the hematocrit tubes in an ultra-low (–80°C) freezer. Because of the limited amount of blood available for hormone analysis, we analyzed blood from male birds for testosterone and blood from female birds for thyroxine. From male blood samples, we extracted testosterone using diethyl ether and then analyzed for testosterone using a Cayman EIA kit (catalogue no. 582701, Cayman Chemical, Ann Arbor, Michigan). From female blood samples, we analyzed for total thyroxine (T4) using a sensitive-T4 Monobind EIA kit (catalogue no. 3425-300, Monobind, Costa Mesa, California). We validated EIA kits using goldfinch plasma collected from a previous captive colony. We used multivariate, repeated-measures analysis of variance (MANOVA) to test for overall treatment and sex effects, with additional Dunnett’s tests to compare the treatment groups with the control group in each period. Testosterone data were log transformed to meet the assumptions of normality. Given that the different housing situation for males may have influenced parameters, each variable was tested for differences

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between males paired with other males and males paired with females using repeated-measures ANOVAs and two-sample t-tests at each sampling period. For color measurements, we averaged the two readings taken at each body region to get a mean estimate and analyzed the data separately by sex because of notable sex differences in plumage color (Middleton 1993). We calculated three standard descriptors of reflectance spectra (brightness, hue, and chroma) in the 300- to 700-nm spectral range. Because goldfinch plumage and integument show reflectance peaks in both the ultraviolet (UV; 300–400 nm) and human-visible (400–700 nm) ranges, analyses were separated for these two ranges. For brightness, we calculated the mean reflectance for each spectral range of interest. We calculated hue as the wavelength at peak reflectance (λRmax) or at maximum slope for reflectance curves that plateau (Siefferman and Hill 2003, Stein and Uy 2006). Because the foot reflectance spectra contained a double peak in the visual range, hue was calculated for the UV range only. We calculated chroma as the ratio of the total reflectance in the range of interest and the total reflectance of the entire spectral range. Thus, we calculated UV chroma as R300−400/ R300−700 and the visible chroma as R400−700/R300−700. R esults Males’ testosterone concentrations did not differ significantly among groups, from the initial increase in concentrations in March (F = 0.452, df = 3 and 27, P = 0.718; Appendix 1) to the period of peak concentrations in June (F = 0.255, df = 3 and 21, P = 0.857). Sample sizes varied as a result of insufficient blood collection or loss of samples during centrifugation. Thyroxine concentrations among female birds differed with treatment (F = 3.382, df = 3 and 14, P = 0.048; Fig. 1); the plasma T4 concentrations of control-group birds overall were greater than those of the linurontreated birds. The control-group T4 concentrations rose steadily throughout the treatment period, whereas those of the treated birds showed an uneven pattern over time, decreasing at various intervals, including after the onset of treatment for the mediumand high-dose groups (Fig. 1). Progression of the orange coloration into the bill did not differ significantly (F = 1.449, df = 3 and 48, P = 0.240; Appendix 1) among treatment groups, and all groups approached near maximum levels of progression by the beginning of June. Progression differed between males and females (F = 34.436, df = 1 and 48, P = 0.000), with males displaying more orange than females. Plumage and integument showed no significant differences in mean reflectance or chroma among treatment groups. As for hue, there were significant differences in the UV range of the male dorsal plumage (F = 4.945, df = 3 and 32, P = 0.006; Appendix 2) and in the UV range of the female ventral plumage (F = 3.887, df = 3 and 16, P = 0.029; Appendix 2). Dunnett’s tests, however, showed no differences from the control group. Body mass did not differ significantly experiment-wide (F = 1.833, df = 3 and 48, P = 0.154), and there were no sex differences in body mass (F = 0.738, df = 1 and 48, P = 0.395). However, the highdose group weighed significantly more than the control group immediately after onset of treatment (Fig. 2) and generally maintained a higher body mass than the rest of the groups throughout the treatment period.


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Fig. 1. Thyroxine levels of female American Goldfinches exposed to linuron (only control and high-dose groups are shown). Error bars represent standard error (SE) around means. Darkened portion of the bar above the figure indicates period of exposure.

Fig. 2.� �� Body mass of male and female American Goldfinches exposed to linuron (only control and high-dose groups are shown). A significant difference from the control group (Dunnett’s test; P ≤ 0.05) is indicated by an asterisk. Error bars represent standard error (SE) around means. Darkened portion of the bar above the figure indicates period of exposure.

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Fig. 3. Molt progression of male and female American Goldfinches exposed to linuron (only control and high-dose groups are shown). Significant differences from the control group (using Dunnett’s test) are indicated by asterisks (**P ≤ 0.01 and ***P ≤ 0.001). Error bars represent standard error (SE) around means. Darkened portion of the bar above the figure indicates period of exposure.

There was no treatment effect on molt score (F = 0.547, df = 3 and 48, P = 0.652), but the medium- and high-dose groups showed a delay in molt peak (Fig. 3; only the high-dose group shown), the peak for these two groups occurring one sampling period later than either the control or low-dose groups (only control is shown). For the high-dose group, in particular, most of the molt cycle occurred at a later period than in the other groups, and moltprogression scores differed significantly from the control group throughout most of the molting period (Fig. 3). Molt scores differed significantly between males and females (F = 4.870, df = 1 and 48, P = 0.032), but there was no interaction effect with treatment and sex (F = 0.569, df = 3 and 48, P = 0.638). Hematocrit also differed according to treatment (F = 4.555, df = 3 and 28, P = 0.010; Fig. 4). For the control and low-dose groups, hematocrit values marginally increased at the beginning of June, whereas the medium-dose group’s values stayed within the same range as previous sampling periods and the high-dose group’s values decreased at this time. The high-dose group also had lower hematocrit values than all other groups during the treatment period. Hematocrit values in males and females were not different (F = 1.215, df = 1 and 28, P = 0.280). Few significant differences were found between males housed with other males and males housed with females. No differences were found with any variable when compared across the entire sampling period. At individual sampling dates, males housed in male– male pairs weighed less than males housed in male–female pairs (separate-variance t-test, t = −2.165, df = 25.1, P = 0.040) on the last sampling date (in August, post-treatment), and males housed in


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Fig. 4. Hematocrit of male and female American Goldfinches exposed to linuron (only control and high-dose groups are shown). Significant differences from the control group (using Dunnett’s test) are indicated by asterisks (*P ≤ 0.05 and ***P ≤ 0.001). Darkened portion of the bar above the figure indicates period of exposure.

male–male pairs had lower molt scores than males housed in male– female pairs at the end of June (separate-variance t-test, t = −2.258, df = 28.8, P = 0.032) and at the beginning of July (post-treatment) (separate-variance t-test, t = −2.115, df = 24.8, P = 0.045). D iscussion In American Goldfinches, linuron affected a range of physiological parameters, including molt progression, hematocrit, and plasma T4 concentrations (compared only in female birds). The present study provides evidence that linuron has endocrine-active effects in goldfinches, though the exact physiological mechanism(s) by which linuron acts in this species remain unclear. In rats, linuron is considered to have both antiandrogenic (Gray et al. 1999) and antithyroid effects (Rehnberg et al. 1988, O’Connor et al. 2002). Hormones.—In females, the treated groups generally had lower plasma T4 concentrations than the control group. These results are similar to those of studies that showed reductions in thyroid hormones with linuron treatment in rodents (Rehnberg et al. 1988, O’Connor et al. 2002). Lower thyroid hormone concentrations, especially during particular periods, can have negative consequences for young and adult birds. The absence of thyroid hormones during early life stages can stunt growth and affect skeletal and nervoussystem development (Lothrop 1996). In adult birds, seasonal gonadal activity depends on normal thyroid function (Höhn 1961). Thyroidectomy or a thyroid deficiency can impair reproductive success (e.g., decrease eggshell thickness, reduce testicular weight; Höhn 1961, Lothrop 1996). Altered T4 concentrations may also

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disrupt other events known to be influenced by thyroid hormones, such as the termination of the breeding period, postnuptial molt, and physiological preparation for migration (Pant and ChandolaSaklani 1993, Wilson and Reinert 1996, Bentley 1997). In the present study, linuron had no significant effect on plasma testosterone concentrations. All groups showed a normal increase during spring and reached peak concentrations during the summer breeding season. In rodents, linuron has antiandrogenic effects, but only at high doses (150 mg kg−1 day−1) are testosterone concentrations decreased (O’Connor et al. 2002); lower doses have no effect on testosterone concentrations (Cook et al. 1993, Lambright et al. 2000). The highest dose used in the present study was ~9× lower than 150 mg kg−1 day−1, so the doses may have been too low to alter testosterone concentrations. Bill, plumage, and integument coloration.—Given that there was no significant treatment effect on plasma testosterone concentrations in the present study, it is not surprising that there was also no treatment effect on bill carotenoid progression. In some avian species, including the goldfinch (Mundinger 1972), bill color is responsive to changes in androgen concentrations (Witschi 1961, Cynx and Nottebohm 1992). Linuron also did not appear to greatly affect plumage or integument color. There were no differences in mean reflectance or chroma of plumage and integument body-regions. There were some differences in plumage hue, but only in the UV range. The fact that there were no differences between the treatment groups and the control group, however, suggests that the differences may be attributable to reasons other than linuron exposure. Although thyroxine can affect integument and plumage coloration (Voitkevich 1966), including carotenoid-based coloration (Oglesbee 1992), most of the evidence shows thyroxine altering melanin-based coloration (Kimball 2006). Thus, the alterations in thyroxine concentration would not necessarily be expected to affect the carotenoid-based plumage of this species. Body mass.—Body mass did not differ significantly among groups. In comparing groups at separate periods, however, the high-dose group initially had a significantly greater body mass than the control group after the onset of treatment. The highdose group also maintained a stable weight of ~14 g throughout the study until taken off treatment, at which time the mean body weight decreased by >1 g and was nearly equal to that of the control group. The generally higher body mass for the treatment groups compared with the control group suggests a possible thyroid influence. The significant increase in body mass for the high-dose group occurred at the same time that females’ T4 concentrations decreased, and studies have shown that decreased thyroid activity could lead to slower metabolic rate and increased fat deposition (Thapliyal et al. 1973, Ringer 1976, Oglesbee 1992). That the high-dose group maintained a relatively heavy body mass throughout the treatment period is contrary to what has been observed in studies using rodents (Cook et al. 1993, ScassellatiSforzolini et al. 1994). However, much higher doses were used in those studies, and one possible explanation is that the body-mass reductions may have been a result of toxic effects leading to a reduction in food intake. Molt.—Although all groups completed a full molt, linuron had a dose-dependent effect on molt progression. Although the low-dose group had a similar progression pattern to that of the control group, both the medium and the high-dose groups showed


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a later molt peak (about three weeks after the control and low-dose groups). For the high-dose group, the effect was apparent in early April, when this group had little molt activity, whereas the rest of the groups were at or near a moderate stage of molt. For wild birds, any delay in molt schedule could prove costly by disrupting the normal use and balance of energy reserves for molt and migration. Additionally, a delayed prealternate molt close to the breeding season could hinder mating success (Omland 1996, Robertson et al. 1998). In many species, thyroid hormones play a primary role in molt and feather regeneration (Payne 1972, Pant and ChandolaSaklani 1992), with low T4 concentrations delaying or preventing the molt process (Oglesbee 1992). The present study indicates that altered T4 concentrations in the treated groups (as demonstrated in the females) may have affected molt. In addition to thyroid hormones, the regulation of molt (timing of onset, intensity, and duration) may be influenced by several interconnecting factors, including food availability (Richardson and Kaminski 1992), photoperiod (Farner et al. 1980, Dawson 1994), and reproductive hormones (Runfeldt and Wingfield 1985, Nolan et al. 1992). However, it is unlikely that any differences in molt progression were attributable to the above-cited factors, given that all groups were treated in the same manner (e.g., equal food rations and outdoor housing) and no differences in male testosterone concentrations were found among groups. Given that there were no differences between males and females in response to treatment, it is likely that estradiol and other reproductive hormones were also unaffected. Hematocrit.—Although hematocrit can vary seasonally with events such as migration (Morton 1994, Saino et al. 1997), molt (deGraw et al. 1979, Morton 1994), and reproduction (Bedrak et al. 1981, Morton 1994, Hõrak et al. 1998), it is often used as a healthstatus indicator (Sánchez-Guzmán et al. 2004). An anemic (low hematocrit) condition usually indicates a decrease in production, excessive loss, or destruction of red blood cells. Exposure to toxicants has been shown to lower hematocrit (Hoffman et al. 1985). In the present study, hematocrit was affected by linuron treatment. Hematocrit in the high-dose group decreased after onset of treatment and remained below the levels found in all other groups throughout the treatment period. By contrast, there was an increase in hematocrit during summer months for the control and low-dose groups, and there was no change in hematocrit during this time for the medium-dose group. The finding that the high-dose group generally had the greatest mean body mass but the lowest hematocrit values throughout the treatment period contrasts with the results from another study, which found a positive association of hematocrit with body mass (Sánchez-Guzmán et al. 2004). Studies with rodents and dogs have shown that linuron can negatively affect hematological parameters, including decreasing hematocrit values (Hodge et al. 1968, Caux et al. 1998). These effects are likely related to linuron’s ability to cause red-blood-cell hemolysis or bone-marrow toxicity (Hodge et al. 1968, Scassellati-Sforzolini et al. 1997). However, a decrease in hematocrit may also be related to a decrease in the concentration of thyroid hormones. Anemia can result from hypothyroidism (Oglesbee 1992) and, in general, thyroid hormones stimulate erythropoiesis (Popovic et al. 1977, Sullivan and McDonald 1992). We have shown that exposure to linuron can produce subtle physiological alterations in an avian species that could affect a bird’s

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fitness in realistic environmental conditions. The fact that the effects were seen at relatively low doses raises the question of whether more attention to chemical effects at lower dose levels is needed. Low-dose examination may be especially important for contaminants such as pesticides, considering the likelihood of low-concentration avian exposure during pesticide-application events (Blus et al. 1989, White et al. 1990). The only documented case of linuron exposure in wild avian species reported lowlevel tissue concentrations (range: 0.06–0.14 parts per million; Bridges and Andrews 1977). However, linuron’s ability to persist in certain environmental conditions (Caux et al. 1998) and its use in agricultural areas and along roadsides (Short and Colborn 1999) suggest that additional avian species are routinely exposed. Furthermore, most pesticide-related effects on wildlife are not observed, even in severe cases such as acute mortality (Vyas 1999). Thus, detection of sublethal effects, such as endocrine disruption, would be difficult and rare under field conditions. Given that pesticides are used in large amounts worldwide and that many of their active or inert ingredients are EACs (Short and Colborn 1999, Racke 2003), continued awareness and further study by the scientific community regarding the range of potential effects and effective concentrations of EACs is important. Acknowledgments We thank staff members of the U.S. Geological Survey (USGS) Patuxent Wildlife Research Center, including W. Bauer, D. Graham, and K. Schlansker, for their help with the care of the captive goldfinch colony, and G. Olsen for providing veterinary assistance. We also thank all who provided useful comments on this manuscript, including E. Synder and several anonymous reviewers, and N. Ostiguy for her assistance with statistical analysis. Funding for this research was provided by the USGS Biological Resources Division and the Pennsylvania Agricultural Experiment Station. Literature Cited Anfossi, P., P. Roncada, G. L. Stracciari, M. Montana, C. Pasqualucci, and C. Montesissa. 1993. Toxicokinetics and metabolism of linuron in rabbit: In vivo and in vitro studies. Xenobiotica 23:1113–1123. Bedrak, E., S. Harvey, and A. Chadwick. 1981. Concentrations of pituitary, gonadal and adrenal hormones in serum of laying and broody white rock hens (Gallus domesticus). Journal of Endocrinology 89:197–204. Bentley, G. E. 1997. Thyroxine and photorefractoriness in starlings. Poultry and Avian Biology Reviews 8:123–139. Billard, R. S., and P. S. Humphrey. 1972. Molts and plumages in the Greater Scaup. Journal of Wildlife Management 36:765–774. Blus, L. J., C. S. Staley, C. J. Henny, G. W. Pendleton, T. H. Craig, E. H. Craig, and D. K. Halford. 1989. Effects of organophosphorus insecticides on Sage Grouse in southeastern Idaho. Journal of Wildlife Management 53:1139–1146. Botham, C., P. Holmes, and P. Harrison. 1999. Endocrine disruption in mammals, birds, reptiles and amphibians. Pages 61–82 in Endocrine Disrupting Chemicals (R. E. Hester and R. M. Harrison, Eds.). Issues in Environmental Science and Technology, no. 12. Royal Society of Chemistry, Cambridge, United Kingdom.


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Brawner, W. R., III, G. E. Hill, and C. A. Sundermann. 2000. Effects of coccidial and mycoplasmal infections on carotenoidbased plumage pigmentation in male House Finches. Auk 117: 952–963. Bridges, J. M., and R. D. Andrews. 1977. Agricultural pesticides in Wild Turkeys in southern Illinois. Transactions of the Illinois State Academy Science 69:473–478. Caux, P.-Y., R. A. Kent, G. T. Fan, and C. Grande. 1998. Canadian water quality guidelines for linuron. Environmental Toxicology and Water Quality 13:1–41. Cook, J. C., L. S. Mullin, S. R. Frame, and L. B. Biegel. 1993. Investigation of a mechanism for Leydig cell tumorigenesis by linuron in rats. Toxicology and Applied Pharmacology 119:195–204. Cynx, J., and F. Nottebohm. 1992. Testosterone facilitates some conspecific song discriminations in castrated Zebra Finches (Taeniopygia guttata). Proceedings of the National Academy of Sciences USA 89:1376–1378. Dawson, A. 1994. The effects of daylength and testosterone on the initiation and progress of moult in starlings Sturnus vulgaris. Ibis 136:335–340. deGraw, W. A., M. D. Kern, and J. R. King. 1979. Seasonal changes in the blood composition of captive and free-living White-crowned Sparrows. Journal of Comparative Physiology 129:151–162. Farner, D. S., R. S. Donham, M. C. Moore, and R. A. Lewis. 1980. The temporal relationship between the cycle of testicular development and molt in the White-crowned Sparrow, Zonotrichia leucophrys gambelii. Auk 97:63–75. Freemark, K., and C. Boutin. 1995. Impacts of agricultural herbicide use on terrestrial wildlife in temperate landscapes: A review with special reference to North America. Agriculture, Ecosystems & Environment 52:67–91. Giesy, J. P., L. A. Feyk, P. D. Jones, K. Kannan, and T. Sanderson. 2003. Review of the effects of endocrine-disrupting chemicals in birds. Pure and Applied Chemistry 75:2287–2304. Gray, L. E., C. Wolf, C. Lambright, P. Mann, M. Price, R. Cooper, and J. Ostby. 1999. Administration of potentially antiandrogenic pesticides (procymidone, linuron, iprodione, chlozolinate, p,p’-DDE, and ketoconazole) and toxic substances (dibutyl- and diethylhexyl phthalate, PCB 169, and ethane dimethane sulphonate) during sexual differentiation produces diverse profiles of reproductive malformations in the male rat. Toxicology and Industrial Health 15:94–118. Hipes, D. L., and G. R. Hepp. 1995. Nutrient-reserve dynamics of breeding male Wood Ducks. Condor 97:451–460. Hodge, H. C., W. L. Downs, D. W. Smith, and E. A. Maynard. 1968. Oral toxicity of linuron (3,-(3,4-dichlorophenyl)-1-methoxy1-methylurea) in rats and dogs. Food and Cosmetics Toxicology 6:171–183. Hoffman, D. J., J. C. Franson, O. H. Pattee, C. M Bunck, and H. C. Murray. 1985. Biochemical and hematological effects of lead ingestion in nestling American Kestrels (Falco sparverius). Comparative Biochemistry and Physiology 80C:431–439. Höhn, E. O. 1961. Endocrine glands, thymus and pineal body. Pages 87–114 in Biology and Comparative Physiology of Birds, vol. 2 (A. J. Marshall, Ed.). Academic Press, New York. Hõrak, P., S. Jenni-Eiermann, I. Ots, and L. Tegelmann. �� 1998. Health and reproduction: The sex-specific clinical profile of Great Tits (Parus major) in relation to breeding. Canadian Journal of Zoology 76:2235–2244.

5/19/08 10:00:05 AM

A pril 2008

— E ffects

of

L inuron

Kimball, R. T. 2006. Hormonal control of coloration. Pages 431– 468 in Bird Coloration, vol. I (G. E. Hill and K. J. McGraw, Eds.). Harvard University Press, Cambridge, Massachusetts. Kookana, R. S., H. J. Di, and L. A. G. Aylmore. 1995. A field study of leaching and degradation of nine pesticides in a sandy soil. Australian Journal of Soil Research 33:1019–1030. Lambright, C., J. Ostby, K. Bobseine, V. Wilson, A. K. Hotchkiss, P. C. Mann, and L. E. Gray, Jr. 2000. Cellular and molecular mechanisms of action of linuron: An antiandrogenic herbicide that produces reproductive malformations in male rats. Toxicological Sciences 56:389–399. Lothrop, C. D., Jr. 1996. Diseases of the endocrine system. Pages 368–379 in Diseases of Cage and Aviary Birds, 3rd ed. (W. J. Rosskopf, Jr., and R. W. Woerpel, Eds.). Williams and Wilkins, Baltimore, Maryland. McCarty, J. P., and A. L. Secord. 2000. Possible effects of PCB contamination on female plumage color and reproductive success in Hudson River Tree Swallows. Auk 117:987–995. McGraw, K. J., G. E. Hill, R. Stradi, and R. S. Parker. 2001. The influence of carotenoid acquisition and utilization on the maintenance of species-typical plumage pigmentation in male American Goldfinches (Carduelis tristis) and Northern Cardinals (Cardinalis cardinalis). Physiological and Biochemical Zoology 74:843–852. Middleton, A. L. A. 1993. American Goldfinch (Carduelis tristis). In The Birds of North America, no. 80 (A. Poole and F. Gill, Eds.). Academy of Natural Sciences, Philadelphia, and American Ornithologists’ Union, Washington, D.C. Millam, J. R., C. B. Craig-Veit, M. E. Batchelder, M. R. Viant, T. M. Herbeck, and L. W. Woods. 2002. An avian bioassay for environmental estrogens: The growth response of Zebra Finch (Taeniopygia guttata) chick oviduct to oral estrogens. Environmental Toxicology and Chemistry 21:2663–2668. Morton, M. L. 1994. Hematocrits in montane sparrows in relation to reproductive schedule. Condor 96:119–126. Mundinger, P. C. 1972. Annual testicular cycle of the bill color change in the Eastern American Goldfinch. Auk 89:403–419. Nolan, V., Jr., E. D. Ketterson, C. Ziegenfus, D. P. Cullen, and C. R. Chandler. 1992. Testosterone and avian life histories: Effects of experimentally elevated testosterone on prebasic molt and survival in male Dark-eyed Juncos. Condor 94:364–370. O’Connor, J. C., S. R. Frame, and G. S. Ladics. 2002. Evaluation of a 15-day screening assay using intact male rats for identifying antiandrogens. Toxicological Sciences 69:92–108. Oglesbee, B. L. 1992. Hypothyroidism in a Scarlet Macaw. Journal of the American Veterinary Medical Association 201:1599–1601. Omland, K. E. 1996. Female Mallard mating preferences for multiple male ornaments. I. Natural variation. Behavioral Ecology and Sociobiology 39:353–360. Pant, K., and A. Chandola-Saklani. 1992. Effects of thyroxine on avian moulting may not involve prior conversion to tri-iodothyronine. Journal of Endocrinology 137:265–270. Pant, K., and A. Chandola-Saklani. 1993. A role for thyroid hormones in the development of premigratory disposition in Redheaded Bunting, Emberiza bruniceps. Journal of Comparative Physiology B 163:389–394. Pasquini, R., G. Scassellati-Sforzolini, P. Dolara, L. Pampanella, M. Villarini, G. Caderni, M. Fazi, and C. Fatigoni. 1994. Assay of linuron and a pesticide mixture commonly found


on

G oldfinches —

417

in the Italian diet, for promoting activity in rat liver carcinogenesis. Pharmacology and Toxicology 75:170–176. Payne, R. B. 1972. Mechanisms and control of molt. Pages 103–155 in Avian Biology, vol. 2 (D. S. Farner, J. R. King, and K. C. Parkes, Eds.). Academic Press, New York. Popovic, W. J., J. E. Brown, and J. W. Adamson. 1977. The influence of thyroid hormones on in vitro erythropoiesis. Journal of Clinical Investigation 60:907–913. Racke, K. D. 2003. Release of pesticides into the environment and initial concentrations in soil, water, and plants. Pure and Applied Chemistry 75:1905–1916. Rehnberg, G. L., J. M. Goldman, R. L. Cooper, J. F. Hein, W. K. McElroy, K. C. Booth, and L. E. Gray. 1988. Effect of linuron on the brain-pituitary-testicular reproductive axis in the rat. Toxicologist 8:121. Richardson, D. M., and R. M. Kaminski. 1992. Diet restriction, diet quality, and prebasic molt in female Mallards. Journal of Wildlife Management 56:531–539. Ringer, R. K. 1976. Thyroids. Pages 348–358 in Avian Physiology, 3rd ed. (P. D. Sturkie, Ed.). Springer-Verlag, New York. Robertson, G. J., F. Cooke, R. I. Goudie, and W. S. Boyd. 1998. Moult speed predicts pairing success in male Harlequin Ducks. Animal Behaviour 55:1677–1684. Rolland, R. M. 2000. A review of chemically-induced alterations in thyroid and vitamin A status from field studies of wildlife and fish. Journal of Wildlife Diseases 36:615–635. Runfeldt, S., and J. C. Wingfield. 1985. Experimentally prolonged sexual activity in female sparrows delays termination of reproductive activity in their untreated males. Animal Behaviour 33:403–410. Saino, N., J. J. Cuervo, P. Ninni, F. de Lope, and A. P. Møller. 1997. Haematocrit correlates with tail ornament size in three populations of the Barn Swallow (Hirundo rustica). Functional Ecology 11:604–610. Sánchez-Guzmán, J. M., A. Villegas, C. Corbacho, R. Morán, A. Marzal, and R. Real. 2004. Response of the haematocrit to body condition changes in Northern Bald Ibis Geronticus eremita. Comparative Biochemistry and Physiology A 139: 41–47. Scanes, C. G., S. Harvey, J. A. Marsh, and D. B. King. 1984. Hormones and growth in poultry. Poultry Science 63:2062–2074. Scanes, C. G., and F. M. A. McNabb. 2003. Avian models for research in toxicology and endocrine disruption. Avian and Poultry Biology Reviews 14:21–52. Scassellati-Sforzolini, G., M. Moretti, M. Villarini, S. Monarca, C. Fatigoni, and R. Pasquini. 1994. In vivo studies on enzymatic induction activity of linuron. Journal of Environmental Pathology, Toxicology and Oncology 13:11–17. Scassellati-Sforzolini, G., R. Pasquini, M. Moretti, M. Villarini, C. Fatigoni, P. Dolara, S. Monarca, G. Caderni, F. Kuchenmeister, P. Schmezer, and B. L. Pool-Zobel. 1997. In vivo studies on genotoxicity of pure and commercial linuron. Mutation Research 390:207–221. Short, P., and T. Colborn. 1999. Pesticide use in the U.S. and policy implications: A focus on herbicides. Toxicology and Industrial Health 15:240–275. Siefferman, L., and G. E. Hill. 2003. Structural and melanin coloration indicate parental effort and reproductive success in male Eastern Bluebirds. Behavioral Ecology 14:855–861.

5/19/08 10:00:06 AM

418


Stein, A. C., and J. A. C. Uy. 2006. Plumage brightness predicts male mating success in the lekking Golden-collared Manakin, Manacus vitellinus. Behavioral Ecology 17:41–47. Sullivan, P. S., and T. P. McDonald. 1992. Thyroxine suppresses thrombocytopoiesis and stimulates erythropoiesis in mice. Proceedings of the Society for Experimental Biology and Medicine 201:271–277. Thapliyal, J. P. 1969. Thyroid in avian reproduction. General and Comparative Endocrinology Supplement 2:111–122. Thapliyal, J. P., R. K. Garg, and G. S. R. C. Murty. 1973. Effects of surgical thyroidectomy on the chemical composition of the body and of the plasma of Spotted Munia, Lonchura punctulata. General and Comparative Endocrinology 21:547–553. U.S. Environmental Protection Agency. 1988. Linuron. Pages 484–490 in Pesticide Fact Handbook. Noyes Data Corporation, Park Ridge, New Jersey. U.S. Environmental Protection Agency. 1995. Reregistration eligibility decision (RED): Linuron, List A, Case 0047. EPA �� 738R-95-003. VanGessel, M. J. 1999. �� Control of �� perennial �� weed species �� as �� seed�� lings with soil-applied herbicides. Weed Technology 13:425–428.

and


Voitkevich, A. A. 1966. The Feathers and Plumage of Birds. October House, New York. Vos, J. G., E. Dybing, H. A. Greim, O. Ladefoged, C. Lambré, J. V. Tarazona, I. Brandt, and A. D. Vethaak. 2000. Health effects of endocrine-disrupting chemicals on wildlife, with special reference to the European situation. Critical Reviews in Toxicology 30:71–133. Vyas, N. B. 1999. Factors influencing estimation of pesticide-related wildlife mortality. Toxicology and Industrial Health 15:187–192. White, D. H., J. T. Seginak, and R. C. Simpson. 1990. Survival of Northern Bobwhites in Georgia: Cropland use and pesticides. Bulletin of Environmental Contamination and Toxicology 44:73–80. Wilson, F. E., and B. D. Reinert. 1996. The timing of thyroiddependent programming in seasonally breeding male American Tree Sparrows (Spizella arborea). General and Comparative Endocrinology 103:82–92. Witschi, E. 1961. Sex and secondary sexual characters. Pages 115– 168 in Biology and Comparative Physiology of Birds, vol. 2 (A. J. Marshall, Ed.). Academic Press, New York. Associate Editor: A. M. Dufty, Jr.

Appendix 1. Results (means ± SE of measured parameters) of exposure of male and female American Goldfinches to different doses of linuron (control [c] and 1, 4, and 16 μg g–1 day–1). Sample sizes are given in parentheses. Pretreatment Dose

3/31/03

4/20/03

C 0.17 ± 0.10 (6) 1 0.54 ± 0.40 (4) 4 0.05 ± 0.10 (5) 16 0.10 ± 0.10 (5)

0.37 ± 0.20 (7) 0.57 ± 0.10 (7) 0.42 ± 0.10 (9) 0.53 ± 0.10 (8)

1.38 ± 0.30 (8) 1.63 ± 0.40 (7) 1.42 ± 0.20 (7) 1.53 ± 0.30 (9)

2.43 ± 1.20 (5) 1.02 ± 1.00 (5) 1.77 ± 0.60 (5) 1.30 ± 0.70 (5)

3.67 ± 1.30 (5) 2.84 ± 1.20 (4) 0.40 ± 1.50 (5) 0.43 ± 0.40 (5)

5.90 ± 1.10 (5) 5.98 ± 0.70 (5) 6.38 ± 2.80 (5) 3.64 ± 1.10 (5)

2.84 ± 0.20 (14) 2.24 ± 0.30 (14) 2.81 ± 0.20 (14) 2.72 ± 0.20 (14)

3.64 ± 0.20 (14) 3.20 ± 0.20 (14) 3.45 ± 0.20 (14) 3.52 ± 0.20 (14)

13.14 ± 0.20 (14) 13.31 ± 0.10 (14) 13.11 ± 0.30 (14) 14.04 ± 0.20a (14)

13.33 ± 0.30 (14) 13.46 ± 0.10 (14) 13.51 ± 0.20 (14) 13.96 ± 0.30 (14)

C 1 4 16

3/10/03

During treatment

C 1.76 ± 0.20 (14) 1 1.39 ± 0.30 (14) 4 1.62 ± 0.30 (14) 16 1.96 ± 0.20 (14) C 1 4 16

12.99 ± 0.30 (14) 13.26 ± 0.20 (14) 12.72 ± 0.20 (14) 13.51 ± 0.30 (14)

C 1.64 ± 0.70 (14) 1 1.50 ± 0.60 (14) 4 2.93 ± 0.70 (14) 16 1.14 ± 0.30 (14) C 1 4 16

49.46 ± 1.10 (13) 52.27 ± 0.90 (11) 52.36 ± 1.30 (11) 51.75 ± 0.80 (12)

5.86 ± 0.90 (14) 10.57 ± 0.50 (14) 6.00 ± 0.90 (14) 10.86 ± 0.50 (14) 5.00 ± 0.90 (14) 9.71 ± 0.50 (14) 1.43 ± 0.40c (14) 6.21 ± 1.00c (14) 54.38 ± 1.20 (13) 54.89 ± 1.30 (9) 52.75 ± 1.30 (12) 49.85 ± 0.90a (13)

53.15 ± 1.20 (13) 54.69 ± 1.10 (13) 53.77 ± 1.10 (13) 51.36 ± 1.00 (14)

5/10/03

Post-treatment 6/1/03

6/23/03

Testosterone (males only) 1.61 ± 0.20 (8) 2.22 ± 0.20 (7) 2.18 ± 0.20 (7) 1.78 ± 0.40 (5) 2.14 ± 0.20 (7) 2.01 ± 0.40 (6) 1.60 ± 0.20 (7) 2.39 ± 0.20 (6) 2.26 ± 0.10 (5) 1.37 ± 0.20 (8) 2.27 ± 0.20 (5) 2.18 ± 0.20 (6) Thyroxine (females only) 8.26 ± 1.60 (5) 12.02 ± 2.00 (5) 12.88 ± 1.30 (4) 3.56 ± 1.10 (5) 10.48 ± 0.80 (5) 9.17 ± 1.00a (5) 7.16 ± 1.70 (5) 10.02 ± 1.60 (5) 8.46 ± 0.40a (5) 3.34 ± 1.30 (5) 8.14 ± 0.40 (5) 9.91 ± 1.20 (5) Bill color progression 4.11 ± 0.20 (14) 4.31 ± 0.10 (14) 4.21 ± 0.10 (14) 3.87 ± 0.20 (14) 4.31 ± 0.10 (14) 4.26 ± 0.10 (14) 3.96 ± 0.20 (14) 4.26 ± 0.10 (14) 4.31 ± 0.10 (14) 3.91 ± 0.20 (14) 4.00 ± 0.30 (14) 4.21 ± 0.20 (14) Body mass 13.57 ± 0.40 (14) 13.41 ± 0.30 (14) 13.16 ± 0.30 (14) 13.81 ± 0.40 (14) 14.19 ± 0.50 (14) 13.79 ± 0.30 (14) 13.36 ± 0.30 (14) 13.91 ± 0.30 (14) 13.31 ± 0.30 (14) 13.99 ± 0.30 (14) 14.16 ± 0.20 (14) 13.97 ± 0.20 (14) Molt score 8.57 ± 0.80 (14) 4.79 ± 0.80 (14) 3.79 ± 0.70 (14) 7.93 ± 0.60 (14) 4.79 ± 0.90 (14) 2.93 ± 0.70 (14) 10.86 ± 0.50a (14) 5.21 ± 0.70 (14) 2.29 ± 0.60 (14) 11.71 ± 0.10c (14) 8.57 ± 0.60b (14) 3.93 ± 0.70 (14) Hematocrit 54.77 ± 1.00 (13) 57.64 ± 1.30 (14) 56.08 ± 1.40 (12) 55.91 ± 0.70 (11) 60.17 ± 1.20 (12) 58.15 ± 1.20 (13) 55.77 ± 0.70 (13) 55.46 ± 0.90 (13) 55.75 ± 1.20 (12) 52.50 ± 0.70 (14) 49.38 ± 0.90c (13) 52.57 ± 1.20 (14)

7/20/03

8/9/03

2.70 ± 0.20 (6) 2.40 ± 0.20 (6) 2.63 ± 0.20 (8) 2.41 ± 0.20 (7)

1.42 ± 0.40 (6) 1.55 ± 0.20 (6) 1.12 ± 0.20 (8) 1.78 ± 0.30 (7)

10.10 ± 2.10 (5) 8.94 ± 1.30 (5) 9.51 ± 0.60 (4) 7.49 ± 1.30 (5)

10.62 ± 1.50 (5) 8.96 ± 0.80 (5) 9.51 ± 1.50 (4) 10.46 ± 1.30 (5)

4.43 ± 0.20 (14) 4.32 ± 0.20 (13) 4.21 ± 0.20 (12) 4.32 ± 0.20 (14)

4.54 ± 0.10 (14) 4.52 ± 0.20 (13) 4.28 ± 0.10 (12) 4.14 ± 0.20 (12)

12.92 ± 0.30 (14) 13.81 ± 0.40 (13) 12.93 ± 0.30 (12) 12.89 ± 0.20 (14)

13.41 ± 0.30 (14) 13.87 ± 0.30 (13) 13.33 ± 0.30 (12) 13.15 ± 0.30 (13)

1.43 ± 0.40 (14) 1.23 ± 0.50 (13) 0.67 ± 0.20 (12) 0.50 ± 0.20 (14)

0.93 ± 0.40 (14) 1.15 ± 0.60 (13) 0.17 ± 0.10 (12) 0.31 ± 0.10 (13)

52.86 ± 1.60 (14) 55.23 ± 1.10 (13) 55.58 ± 0.90 (12) 55.33 ± 0.90 (12)

55.08 ± 1.30 (12) 56.92 ± 0.80 (13) 54.83 ± 0.90 (12) 56.25 ± 0.60 (12)

Significant difference from the control group (Dunnett’s test, P ≤ 0.05). Significant difference from the control group (Dunnett’s test, P ≤ 0.01). c Significant difference from the control group (Dunnett’s test, P ≤ 0.001). a

b


5/19/08 10:00:08 AM


17.60 ± 1.15 16.40 ± 1.59 16.00 ± 1.66 14.50 ± 1.46

24.00 ± 1.22 22.90 ± 2.23 22.20 ± 1.42 22.50 ± 2.09

11.00 ± 0.68 10.80 ± 0.77 11.80 ± 1.26 9.26 ± 0.83

2.00 ± 0.89 3.50 ± 0.48 1.7 ± 0.46 2.20 ± 0.80

Ventral C 1 4 16

Bill C 1 4 16

Foot C 1 4 16

UV

4.70 ± 0.87 7.40 ± 0.63 4.60 ± 0.93 5.30 ± 1.14

1.90 ± 1.31 2.20 ± 1.24 4.30 ± 1.46 1.80 ± 0.48

4.50 ± 1.48 5.60 ± 1.50 8.90 ± 1.95 4.80 ± 0.77

10.40 ± 0.93 11.90 ± 1.14 12.90 ± 2.14 12.70 ± 2.44 350.00 ± 6.37 367.00 ± 6.50 368.00 ± 8.50 360.00 ± 8.14

364.00 ± 1.33 362.00 ± 1.70 364.00 ± 2.14 361.00 ± 1.44    

603.00 ± 1.06 607.00 ± 6.35 605.00 ± 1.43 601.00 ± 2.40

577.00 ± 12.85 592.00 ± 11.38 557.00 ± 10.25 577.00 ± 12.84

589.00 ± 13.19 599.00 ± 10.59 563.00 ± 8.93 580.00 ± 13.19

Visual 596.00 ± 9.29 588.00 ± 4.96 609.00 ± 16.40 587.00 ± 5.55

Visual

350.00 ± 7.91 369.00 ± 12.75 375.00 ± 8.19 362.00 ± 7.73

   

356.00 ± 1.68 600.00 ± 4.84 362.00 ± 2.26 615.00 ± 10.62 360.00 ± 1.40 606.00 ± 11.47 355.00 ± 5.25 595.00 ± 5.46

363.00 ± 1.99 565.00 ± 15.4 380.00 ± 5.98 551.00 ± 12.12 370.00 ± 6.18 521.00 ± 17.07 360.00 ± 2.11 562.00 ± 13.80

333.00 ± 11.39 349.00 ± 14.09 357.00 ± 16.18 343.00 ± 13.91

UV

0.09 ± 0.02 0.12 ± 0.01 0.08 ± 0.02 0.09 ± 0.02

0.18 ± 0.00 0.19 ± 0.01 0.18 ± 0.00 0.18 ± 0.01

0.17 ± 0.01 0.17 ± 0.01 0.16 ± 0.01 0.16 ± 0.01

0.14 ± 0.01 0.15 ± 0.00 0.14 ± 0.01 0.13 ± 0.01

UV

Visual

0.88 ± 0.03 0.82 ± 0.01 0.88 ± 0.03 0.87 ± 0.03

0.76 ± 0.01 0.74 ± 0.01 0.75 ± 0.01 0.76 ± 0.01

0.78 ± 0.01 0.78 ± 0.01 0.80 ± 0.01 0.79 ± 0.02

0.83 ± 0.01 0.81 ± 0.01 0.84 ± 0.01 0.85 ± 0.02

Males

0.08 ± 0.03 0.07 ± 0.03 0.12 ± 0.02 0.10 ± 0.01

0.18 ± 0.01 0.19 ± 0.01 0.19 ± 0.01 0.20 ± 0.01

0.15 ± 0.01 0.14 ± 0.01 0.16 ± 0.01 0.17 ± 0.01

0.04 ± 0.03 0.10 ± 0.02 0.09 ± 0.03 0.06 ± 0.03

UV

0.90 ± 0.04 0.88 ± 0.05 0.82 ± 0.03 0.86 ± 0.01

0.77 ± 0.01 0.73 ± 0.01 0.74 ± 0.02 0.73 ± 0.01

0.78 ± 0.02 0.79 ± 0.01 0.77 ± 0.02 0.77 ± 0.001

0.94 ± 0.04 0.86 ± 0.03 0.87 ± 0.05 0.91 ± 0.04

Visual

Females

on

7.40 ± 0.89 9.10 ± 1.00 9.70 ± 1.52 9.70 ± 1.65

358.00 ± 1.56 363.00 ± 2.07 358.00 ± 1.96 356.00 ± 2.12

354.00 ± 1.56 356.00 ± 1.90 350.00 ± 0.62 351.00 ± 0.76

UV

Females

L inuron

15.60 ± 0.93 14.40 ± 0.99 16.40 ± 1.71 12.90 ± 1.10

21.80 ± 3.58 25.50 ± 3.80 18.10 ± 1.94 22.80 ± 1.55

3.60 ± 1.29 8.00 ± 2.24 7.40 ± 1.78 5.00 ± 1.06

Visual

Males

Chroma

of

12.90 ± 2.87 13.60 ± 2.75 10.70 ± 0.86 15.00 ± 1.71

1.00 ± 0.82 3.30 ± 1.37 3.30 ± 1.67 1.50 ± 0.70

Females

Hue

— E ffects

36.40 ± 1.41 35.00 ± 2.31 37.10 ± 2.18 35.00 ± 1.15

32.60 ± 1.42 29.00 ± 2.36 31.20 ± 1.80 30.10 ± 2.27

UV

Mean reflectance

Visual

Males

Dorsal C 1 4 16

Body area and dose

Appendix 2. Spectral data (means ± SE of measured parameters) from the plumage and integument of American Goldfinches exposed to different doses of linuron (control [c] and 1, 4, and 16 μg g–1 day–1; n = 9 males and 5 females).

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