Showing papers in "Virginia journal of science in 2014"

A Comparison of Techniques Measuring Stress in Birds

Abstract: Free-living birds are subjected to both external and internal stresses which can affect their health, activity, and reproductive success. To study stress in free living birds, they must be captured in nets and handled by the researcher to take blood samples for commonly used measures of stress, an activity which itself can induce stress and confound results. This study compares the effects of handling time on three different measures of stress: levels of the stress hormone corticosterone (CORT), levels of Heat Shock Protein 60 (HSP 60) and the ratio of heterophils to lymphocytes (H/L ratio) in tufted titmouse (Baeolophus bicolor) captured at feeders between December and January (2011-2013) in Fredericksburg, VA. Blood samples collected between two and 15 minutes from 12 birds were assayed for levels of CORT and HSP and from 24 birds for H/L ratios. Relationships were examined between these stress indicators and handling time, body mass and body condition. CORT was significantly correlated with handling time (p<0.01), which reinforces existing evidence of CORT’s sensitivity to the way subjects are handled immediately prior to blood collection. HSP or H/L ratios were not affected by handling time, suggesting that they may be preferable indicators of stress in free living birds under some circumstances. INTRODUCTION Free-living birds face a variety of internal and external sources of stress, which may affect physiological function and reduce fitness. Acute stress results from a specific stressful event, such as an attack by a predator or sudden storms, whereas chronic stress results from prolonged exposure to biologically challenging conditions, such as exposure to extreme temperatures (Vleck et al. 2000), periods of limited food availability (Herring et al. 2011), and anthropogenic pressures such as pollution, habitat disturbance (Arriero et al. 2008; Busch and Hayward 2009), and from prolonged psychosocial stressors (Cyr et al. 2007; Cyr and Romano 2007; Landys et al. 2011). To Corresponding author: dodell@umw.edu 1 Virginia Journal of Science, Vol. 65, No. 3, 2014 http://digitalcommons.odu.edu/vjs/vol65/iss3 134 VIRGINIA JOURNAL OF SCIENCE cope with such stressors, birds and other animals have a protective physiological stress response that allows them to withstand immediate threats to their homeostatic balance. When this response is elevated chronically, however, it can become biologically costly and have negative impacts on birds’ fitness by weakening the immune system (Dabbert et al. 1997), which could increase susceptibility to disease, and compromising growth and reproduction (Sapolsky et al. 2000). Thus, stress levels can indicate the general physiological condition of birds and point to possible environmental perturbations. Biomarkers such as the glucocorticoid corticosterone (CORT), heterophil/lymphocyte ratios (H/L), and heat shock proteins (HSPs) have all been used as tools to assess chronic or long-term stress in wild populations. These markers may be predictably regulated according to environmental conditions and various biological challenges (Gross and Siegel 1983; Sapolsky et al. 2000; Vleck et al. 2000; Moreno et al. 2002; Martinez-Padilla et al. 2004; Tomas et al. 2004; Davis 2005; Herring and Gawlik 2007; Busch and Hayward 2009; Cockrem et al. 2009; Krams et al. 2010; Herring et al. 2011), and thus can provide researchers with consistent methods of detecting stress experienced by birds in their natural habitats. However, they may also be affected to varying degrees by acute stress caused by capture and handling leading up to blood sample collection. Therefore, drawing inferences about birds’ long-term stress status prior to their capture by researchers may be problematic since the relationships between the different measures used have not been adequately studied. Quantifying glucocorticoids, such as CORT, is presently the most frequently applied method of assessing individual stress in birds (Sapolsky et al. 2000; Tomas et al. 2004; Herring and Gawlik 2007). However, the release of CORT is highly influenced by acute stress associated with capture and handling during field research which may confound results. Capture and handling can rapidly mobilize CORT, which can make the interpretation of CORT measurements difficult under some circumstances (Sapolsky et al. 2000; Romero and Reed 2005; Fridinger et al. 2007; Herring and Gawlik 2007; Busch and Hayward 2009; Cockrem et al. 2009). When handling time before sampling lasts for more than 2 or 3 minutes, CORT levels may no longer accurately reflect birds’ physiological status before their capture (Romero and Reed 2005; Cockrem et al. 2009). In studies involving free-living birds, field conditions may prevent sufficiently prompt blood collection, leading to less reliable measures of chronic stress. Additionally, fecal CORT, can degrade over time in frozen samples (Herring et al. 2007) which reduces reliability of measurements. Herring and Gawlick (2007) compared the use of CORT with that of HSPs as ways of measuring stress associated with allostatic overload (when the energy requirements needed to maintain homeostasis in the body exceed the capacity of the animal) and concluded that HSPs have some advantages over CORT and may represent a viable supplementary or even alternative indicator of chronic stress. Circulating H/L ratios have also been used to measure chronic stress in birds. These ratios are used because the avian immune response to stress takes significantly longer to initiate, by hours to days, than the rapid CORT response, and changes in leukocyte numbers last longer than changes in CORT levels (Davis et al. 2008). Their slower response to stress and longer endurance indicate that H/L ratios may be informative, especially in obtaining baseline stress measurements. However H/L levels are impacted by disease and infection and may not reflect true levels of stress to external stressors. While studies on Adélie penguins (Vleck et al. 2000) and house finches (Davis 2005) Virginia Journal of Science, Vol. 65, No. 3, 2014 http://digitalcommons.odu.edu/vjs/vol65/iss3 MEASURING STRESS IN BIRDS 135 indicate that H/L ratios are resistant to handling up to 1 hour, a study investigating wintering male great tits (Cirule et al. 2012) found that acute stress due to capture and handling caused an increase in heterophil counts between 30 and 60 minutes and a decline in lymphocyte counts between 60 and 120 minutes after capture. Therefore, H/L changes may be species specific and may change more rapidly than originally thought, which may limit the reliability of results in a way similar to CORT. A different cellular response to stress is mediated by HSPs. HSPs are a family of proteins whose expression is increased when cells are exposed to both cellular stressors such as parasites (Merino et al. 1998; Martinez-Padilla et al. 2004; Arriero et al. 2008; del Cerro et al. 2010), limited food availability (Zulkifli et al. 2002; Herring et al. 2011), and sibling competition (Martinez-Padilla et al. 2004; Merino et al. 2006) as well as psychosocial stressors such as crating in birds (Zulkifli et al. 2009), fear (AlAqil et al. 2013) and social interactions in fish (Currie et al. 2009). They have been found to exist in almost all organisms, including bacteria, plants, and animals (Feder and Hofmann 1999). HSPs are a special class of proteins referred to as molecular chaperones which protect proteins from degradation and correct damage caused by stress-induced instability (Merino et al. 1998; Feder and Hofmann 1999; Tomas et al. 2004; del Cerro et al. 2010). Essentially, they serve to restore and maintain cellular homeostasis during times of increased stress (Tomas et al. 2004; del Cerro et al. 2010). These molecules may be reliable indicators of chronic stress because they are maintained at high levels for longer periods after stressors are applied, and some research has shown that handling stress does not cause their rapid up-regulation (Martinez-Padilla et al. 2004; Herring and Gawlik 2007; Herring et al. 2011). However, the resistance of HSPs to acute stress triggered by capture and handling has not been systematically compared to those of CORT and H/L ratios in the same study. The tufted titmouse (Baeolophus bicolor) is a good model species to expand research on the relationships between these three stress indicators and their relative sensitivities to handling time. Close relatives of the tufted titmouse, the blue tit and the great tit, have been used in past studies examining both the intracellular and hormonal stress responses (Arriero et al. 2008; Cockrem et al. 2009; del Cerro et al. 2010). The tufted titmouse is a canopy-dwelling, omnivorous permanent resident species of eastern North American deciduous forests (Grubb and Pravosudov 1994). During the winter, they spend time in flocks of about 2 to 5 individuals. Caching food during cold weather, they commonly frequent feeders and carry 1 seed at a time to store within 40 meters of the feeders, allowing them to be easily captured with mist nets (Grubb and Pravosudov 1994). This study compared the sensitivity of HSP60, CORT, and H/L to acute stress induced by the capture and handling of tufted titmice to evaluate their reliability as tools in avian stress research. The relationships between CORT, H/L ̧ and HSP60 and the time elapsed between capture of subjects and blood collection, as well as the relationships among these bioindicators, were analyzed. We predicted that CORT levels, but not H/L ratios or HSP60 levels, would be positively correlated with handling times longer than 2 minutes after capture of subjects. Finally, we examined whether CORT, H/L, and HSP values were correlated within subjects and related to body condition. Virginia Journal of Science, Vol. 65, No. 3, 2014 http://digitalcommons.odu.edu/vjs/vol65/iss3 136 VIRGINIA JOURNAL OF SCIENCE MATERIALS AND METHODS Capture, Handling, Blood Samp

Survey of the Ectoparasites of the Invasive Small Indian Mongoose (Herpestes auropunctatus [Carnivora: Herpestidae]) on St. John, U.S. Virgin Islands

Abstract: In March 2012, live trapping surveys were conducted for invasive small Indian mongoose (Herpestes auropunctatus) on St. John, U.S. Virgin Islands. Forty mongoose were sampled (31%, 9&) for ectoparasites, and cat fleas (Ctenocephalides felis) were discovered on 17 individuals. There was no difference in the number of ectoparasites per mongoose across age classifications (r = 0.109, P = 0.579). However, males had more cat fleas than females, even when mass was taken into account (males are generally heavier). Future behavioral studies may explain these sex differences. Although management suggestions from this research are limited, these data contribute to an understanding of ectoparasite distributions on these invasive mongoose in the Caribbean. INTRODUCTION The small Indian mongoose (Herpestes auropunctatus) is a 120-1000-gram carnivore, feeding opportunistically on all major vertebrate groups, invertebrates, and occasionally, plants (Lewis et al. 2011). Although uncertainty exists about the extent of its geographic range, this mongoose is believed to be native to the Middle East, India, and Myanmar (Veron et al. 2007). The uncertainty lies in its confusion with a sympatric mongoose, the Javan or small Asian mongoose (H. javanicus), for which H. auropunctatus had been treated as a conspecific. Indeed, nearly all literature published prior to 2007 assumed that the mongoose released onto Hawaiian and Caribbean islands was H. javanicus. However, Veron et al. (2007) confirmed with mtDNA analyses that H. auropunctatus and H. javanicus were two distinct species, and Bennett et al. (2011), definitively determined through mtDNA barcoding that mongoose currently inhabiting Hawaiian and Caribbean islands were H. auropunctatus. Current address: Dept. of Environmental Studies, Univ. of Illinois at Springfield, 1 Springfield, IL 62703 Corresponding author:kpowers4@radford.edu 2 Virginia Journal of Science, Vol. 65, No. 3, 2014 http://digitalcommons.odu.edu/vjs/vol65/iss3 152 VIRGINIA JOURNAL OF SCIENCE The small Indian mongoose was originally introduced in the late 1800s (likely the 1870s) to control the invasive black rat (Rattus rattus) population on St. John, St. Croix, and other nearby Caribbean islands (Nellis and Everard 1983; Horst et al. 2001). The primary diet of mongoose in this region is not the black rat but instead includes native species on the U.S. Virgin Islands (USVI) such as eggs of the brown pelican (Pelicanus occidentalis) and the green sea turtle (Chelonia mydas; Seaman and Randall 1962), and, more commonly, lizards, amphibians, ground-nesting birds, and invertebrates (Nellis 1989; Lewis et al. 2011). Besides hawks (on some islands), the small Indian mongoose has no other natural predators in the USVI, and wildlife managers lack the time, effort, and funds to eradicate the species from the islands (Nellis and Everard 1983). However, as a method of managing for rare breeding birds or reptiles, localized, seasonal removal efforts can be fairly successful. For example, Coblentz and Coblentz (1985) estimated 86% of the mongoose populations were removed in five nights of trapping a number of bays and trails on St. John. However, immigrants and young dispersing mongoose quickly take the place of those lethally removed (Coblentz and Coblentz 1985). If removal efforts only temporarily decrease the mongoose population, what else might negatively impact this invasive species? We suggested that if mongoose on St. John, USVI, carried a heavy parasite load, this could negatively impact the health of the mongoose. Rust and Dryden (1997) report that high flea loadings can cause skin irritation, skin allergies, and anemia in affected individuals. Past studies of mongoose on St. Croix and Puerto Rico found them to be carriers of cat fleas (Ctenocephalides felis), ticks (Ornithodoros puertoricensis), and mange mites (Notoedres cati; Pimentel 1955; Garrett and Haramota 1967; Webb 1980; Corn et al. 1994; Corn et al. 2009). Nellis (1989) states that cat fleas are the most common ectoparasites in the mongoose’s introduced range, and suggests that these fleas were not present in their native habitat in the late 1800s. However, Baldwin et al. (1952) cite a 1934 Hawaiian public health survey, suggesting cat fleas were so common on mongoose on Hawaiian Islands, this animal must be a natural host. With so little natural history research completed on this mongoose in its native range (Horst et al. 2001), absolute confirmation of the cat flea in the native range is not possible. Further, it is clear that flea density varies among locations. Counter to the Hawaiian surveys, Pimentel (1955) found just a single cat flea on 1/210 individuals examined in Puerto Rico. To date, although reported studies of mongoose ectoparasites exist for St. Croix (Webb 1980; Nellis and Everard 1983), Puerto Rico (Pimentel 1955), and Hawaii (e.g., Haas 1966; Garrett and Haramota 1967), we find no published findings of ectoparasites on St. John, USVI, nor their potential negative impact on the mongoose on this island. Further, some studies collected ectoparasites from museum specimens (e.g., Garrett and Haramota 1967), and the authors’ goal was to conclusively determine presence on live individuals. MATERIALS AND METHODS To determine the parasite loads of mongoose on St. John, USVI, the authors livetrapped individuals from 8-10 March 2012 using 45 Tomahawk #202 traps (Tomahawk Virginia Journal of Science, Vol. 65, No. 3, 2014 http://digitalcommons.odu.edu/vjs/vol65/iss3 ECTOPARASITES OF THE INDIAN MONGOOSE 153 Live Trap, Hazelhurst, Wisconsin, USA). Hiking trails in early and late successional habitats were selected, and were restricted to the south-central portion of the island. Sites were at or within 2 km of the Virgin Island Environmental Resource Station (VIERS; UTM Zone 20, 2026684 N, 317964 E). Forty mongoose were captured and combed: 31 males, aged 5.5 – 46 months (AVG. age = 21.4 ± 2.8 [SE]), and 9 females, aged 5.5 – 26 months (AVG. age = 14.3 ± 2.5) via tooth wear (Pearson and Baldwin 1953). Using a flea comb, mongoose fur was brushed for approximately one minute, and ectoparasites were collected. Results, therefore, do not assume that all ectoparasites were collected from each individual; instead, equal brushing effort allowed for a relative comparison among individuals in this study. Collected ectoparasites were stored in 70% ethanol, and transferred back to Radford University for identification. Authors identified the contents of each vial using keys and data from past studies (Webb 1980) and flea guides (Ewing and Fox 1943; De Campos Pereira 2012). This study was approved by the Radford University Institutional Animal Care and Use Committee, protocol #F12-03, and permitted by the National Park Service, VIIS2012-SCI-0001. Arthropod voucher specimens are housed in the Radford University, Biology Department’s Natural History Collection. RESULTS Ectoparasites were discovered on 62.5% of 40 captured individuals (22%, 3&), but authors were only able to capture and preserve the ectoparasites from 18 of these 25 individuals. Such ectoparasite escapes are not uncommon, given the difficulty in sampling live mongoose under sometimes intense field conditions (Haas 1966). Seventeen of the 18 individuals from which ectoparasites were successfully collected harbored cat fleas (Ctenocephalides felis). A single tick of the genus Amblyomma also was documented on the 18 individual; an incomplete specimen prevented th identification to the species level. However, this tick genus was detected on mongoose by Nellis (1989) from the West Indies (specific island not reported) and by Corn et al. (1994; Amblyomma variegatum) in Antigua, West Indies. When examining all 40 individuals for which ectoparasite relative counts (number of ectoparasites per 1 minute of brushing) were available, there was no difference in the number of fleas per mongoose across age classifications (Pearson’s product-moment correlation; r = 0.109, P = 0.579; SAS Institute 2009). However, Student’s t-tests revealed that males had significantly more parasites (AVG number of parasites for %: 1.7 ± 0.4 [SE]) than females (AVG number of parasites for &: 0.4 ± 0.2; t = 2.65, df =19, P = 0.016). Even when mass was taken into account (AVG mass for %: 596 ± 18 g [SE], AVG mass for &: 514 ± 18 g), this gender difference remained in place (Student’s t-test; t = 2.07, df = 16, P = 0.027). DISCUSSION The discovery of the cat flea was not surprising, given its documentation in multiple locations by multiple sources (e.g., Baldwin et al. 1952; Seaman 1963; Haas 1966; Virginia Journal of Science, Vol. 65, No. 3, 2014 http://digitalcommons.odu.edu/vjs/vol65/iss3 154 VIRGINIA JOURNAL OF SCIENCE Webb 1980). However, few reported actual ectoparasite loads, only taxon lists of ectoparasites discovered. Seaman (1963, as reported in Nellis and Everard 1983; AVG = 8.6), Haas (1966; March AVG for %: 4.7, AVG for &: 1.0), and Webb (1980; AVG = 2.7 fleas per mongoose) found similar parasite loads and trends in male vs. female parasite loads. However, with some authors failing to report the methods of parasite sampling (Webb 1980) and others only cursorily describing methods (Haas 1966), direct comparisons of parasite loads across studies may be of little scientific value. Therefore, this study was limited to relative comparisons. This study’s finding that males typically had more parasites than females is in agreement with the findings from these other locales, and this supports their theory that behavioral differences between sexes may impact ectoparasite loads (Haas 1966; Webb 1980). Although Webb (1980) and Haas (1966) suggested that size differences between sexes is a primary reason for unequal parasite load, the statistics from this study suggest that males had greater parasite loads regardless of mass differences. Webb (1980) further suggested that, on St. Croix, this sex difference might be influenced by males’

Phytoplankton in Virginia Lakes and Reservoirs: Part II

Abstract: Phytoplankton composition from 16 Virginia lakes and reservoirs are discussed with emphasis on the dominant taxa, algal bloom producers, and potentially harmful species at these locations. This is a companion study to the more comprehensive publication regarding Virginia freshwater phytoplankton by Marshall (2013).