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Bottini CLJ, Whiley RE, Branfireun BA, MacDougall-Shackleton SA. Effects of sublethal methylmercury and food stress on songbird energetic performance: metabolic rates, molt and feather quality. J Exp Biol 2024; 227:jeb246239. [PMID: 38856174 DOI: 10.1242/jeb.246239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 05/28/2024] [Indexed: 06/11/2024]
Abstract
Organisms regularly adjust their physiology and energy balance in response to predictable seasonal environmental changes. Stressors and contaminants have the potential to disrupt these critical seasonal transitions. No studies have investigated how simultaneous exposure to the ubiquitous toxin methylmercury (MeHg) and food stress affects birds' physiological performance across seasons. We quantified several aspects of energetic performance in song sparrows, Melospiza melodia, exposed or not to unpredictable food stress and MeHg in a 2×2 experimental design, over 3 months during the breeding season, followed by 3 months post-exposure. Birds exposed to food stress had reduced basal metabolic rate and non-significant higher factorial metabolic scope during the exposure period, and had a greater increase in lean mass throughout most of the experimental period. Birds exposed to MeHg had increased molt duration, and increased mass:length ratio of some of their primary feathers. Birds exposed to the combined food stress and MeHg treatment often had responses similar to the stress-only or MeHg-only exposure groups, suggesting these treatments affected physiological performance through different mechanisms and resulted in compensatory or independent effects. Because the MeHg and stress variables were selected in candidate models with a ΔAICc lower than 2 but the 95% confidence interval of these variables overlapped zero, we found weak support for MeHg effects on all measures except basal metabolic rate, and for food stress effects on maximum metabolic rate, factorial metabolic scope and feather mass:length ratio. This suggests that MeHg and food stress effects on these measures are statistically identified but not simple and/or were too weak to be detected via linear regression. Overall, combined exposure to ecologically relevant MeHg and unpredictable food stress during the breeding season does not appear to induce extra energetic costs for songbirds in the post-exposure period. However, MeHg effects on molt duration could carry over across multiple annual cycle stages.
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Affiliation(s)
- Claire L J Bottini
- The University of Western Ontario, Department of Biology, 1151 Richmond St., London, ON, Canada, N6A 5B7
- Advanced Facility for Avian Research, University of Western Ontario, London, ON, N6G 4W4, Canada
| | - Rebecca E Whiley
- The University of Western Ontario, Department of Biology, 1151 Richmond St., London, ON, Canada, N6A 5B7
- Advanced Facility for Avian Research, University of Western Ontario, London, ON, N6G 4W4, Canada
| | - Brian A Branfireun
- The University of Western Ontario, Department of Biology, 1151 Richmond St., London, ON, Canada, N6A 5B7
- Advanced Facility for Avian Research, University of Western Ontario, London, ON, N6G 4W4, Canada
| | - Scott A MacDougall-Shackleton
- Advanced Facility for Avian Research, University of Western Ontario, London, ON, N6G 4W4, Canada
- The University of Western Ontario, Department of Psychology, 1151 Richmond St., London, ON, N6A 5C2, Canada
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Zidat T, Gabirot M, Bonadonna F, Müller CT. Homing and Nest Recognition in Nocturnal Blue Petrels: What Scent May Attract Birds to their Burrows? J Chem Ecol 2023; 49:384-396. [PMID: 37231188 PMCID: PMC10611862 DOI: 10.1007/s10886-023-01424-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/27/2023] [Accepted: 04/05/2023] [Indexed: 05/27/2023]
Abstract
Hypogean petrels return to the same nest burrow to breed on remote islands during the summer months. Their nocturnal behavior at the colony, strong musky odor and olfactory anatomy suggest an important role of olfaction in homing behavior and nest recognition. Behavioral experiments showed that olfactory cues are sufficient to allow nest identification, suggesting a stabile chemical signature emanating from burrows and facilitating nest recognition. However, the chemical nature and sources of this odor remain unknown. To better understand the nest odor composition, we analyzed volatile organic compounds (VOCs) of nests of blue petrels (Halobaena caerulea) derived from three different odor sources: nest air, nest material and feather samples. We also compared, during two successive years, VOCs from burrows with an incubating breeder on the nest, and burrows used during the breeding season by blue petrels but shortly temporally unoccupied by breeders. We found that the nest air odor was mainly formed by the owners' odor, which provided an individual chemical label for nests that appeared stabile over the breeding season. These findings, together with the previous homing behavioral studies showing an essential role of the sense of smell in blue petrels, strongly suggest that the scent emanating from burrows of blue petrels provides the information that facilitates nest recognition and homing.
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Affiliation(s)
- Timothée Zidat
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, CF10 3AX, Cardiff, UK.
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, Université de Tours, IFCE, Nouzilly, France.
| | - Marianne Gabirot
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, CF10 3AX, Cardiff, UK
- ADENA - Réserve Naturelle Nationale du Bagnas, Domaine du Grand Clavelet, Route de Sète, 34300, Agde, France
| | | | - Carsten T Müller
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, CF10 3AX, Cardiff, UK
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Bottini CLJ, Whiley RE, Branfireun BA, MacDougall-Shackleton SA. Effects of methylmercury and food stress on migratory activity in song sparrows, Melospiza melodia. Horm Behav 2022; 146:105261. [PMID: 36126358 DOI: 10.1016/j.yhbeh.2022.105261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 09/01/2022] [Accepted: 09/03/2022] [Indexed: 11/25/2022]
Abstract
Avian migration is a challenging life stage susceptible to the adverse effects of stressors, including contaminants like methylmercury (MeHg). Although birds often experience stressors and contaminants concurrently in the wild, no study to date has investigated how simultaneous exposure to MeHg and food stress affects migratory behavior. Our objectives were to determine if MeHg or food stress exposure during summer, alone or combined, has carry-over effects on autumn migratory activity, and if hormone levels (corticosterone, thyroxine) and body condition were related to these effects. We tested how exposure to dietary MeHg and/or food stress (unpredictable temporary food removal) affected migratory behavior in captive song sparrows, Melospiza melodia. Nocturnal activity was influenced by a 3-way interaction between MeHg × stress × nights of the study, indicating that activity changed over time in different ways depending on prior treatments. Thyroxine was not affected by treatment or sampling date. During the migratory season, fecal corticosterone metabolite concentrations increased in birds co-exposed to MeHg and food stress compared to controls, suggesting an additive carry-over effect. As well, during the period of behavioral recording, body condition increased with time in unstressed birds, but not in stressed birds. Fecal corticosterone metabolite concentrations were positively correlated to duration of nocturnal activity, but thyroxine levels and body condition were not. The differences in nocturnal activity between groups suggest that food stress and MeHg exposure on breeding grounds could have direct and indirect carry-over effects that have the potential to affect the fall migration journey.
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Affiliation(s)
- Claire L J Bottini
- University of Western Ontario, Department of Biology, 1151 Richmond St., London, Ontario N6A 5B7, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada.
| | - Rebecca E Whiley
- University of Western Ontario, Department of Biology, 1151 Richmond St., London, Ontario N6A 5B7, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
| | - Brian A Branfireun
- University of Western Ontario, Department of Biology, 1151 Richmond St., London, Ontario N6A 5B7, Canada
| | - Scott A MacDougall-Shackleton
- Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada; University of Western Ontario, Department of Psychology, 1151 Richmond St., London, Ontario N6A 5C2, Canada
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Grieves LA, Bottini CLJ, Gloor GB, MacDougall-Shackleton EA. Uropygial gland microbiota differ between free-living and captive songbirds. Sci Rep 2022; 12:18283. [PMID: 36316352 PMCID: PMC9622905 DOI: 10.1038/s41598-022-22425-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 10/14/2022] [Indexed: 11/05/2022] Open
Abstract
Symbiotic microbes can affect host behavior and fitness. Gut microbiota have received the most study, with less attention to other important microbial communities like those of scent-producing glands such as mammalian anal glands and the avian uropygial gland. However, mounting evidence suggests that microbes inhabiting scent-producing glands play an important role in animal behavior by contributing to variation in chemical signals. Free-living and captive conditions typically differ in social environment, food diversity and availability, disease exposure, and other factors-all of which can translate into differences in gut microbiota. However, whether extrinsic factors such as captivity alter microbial communities in scent glands remains an open question. We compared the uropygial gland microbiota of free-living and captive song sparrows (Melospiza melodia) and tested for an effect of dietary manipulations on the gland microbiota of captive birds. As predicted, the uropygial gland microbiota was significantly different between free-living and captive birds. Surprisingly, microbial diversity was higher in captive than free-living birds, and we found no effect of dietary treatments on captive bird microbiota. Identifying the specific factors responsible for microbial differences among groups and determining whether changes in symbiotic microbiota alter behavior and fitness are important next steps in this field.
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Affiliation(s)
- L. A. Grieves
- grid.39381.300000 0004 1936 8884Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON N6A 5B7 Canada ,grid.25073.330000 0004 1936 8227Present Address: Department of Biology, McMaster University, 1280 Main St. W, Hamilton, ON L8S 3L8 Canada
| | - C. L. J. Bottini
- grid.39381.300000 0004 1936 8884Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON N6A 5B7 Canada
| | - G. B. Gloor
- grid.39381.300000 0004 1936 8884Department of Biochemistry, The University of Western Ontario, 1151 Richmond St., London, ON N6A 5C1 Canada
| | - E. A. MacDougall-Shackleton
- grid.39381.300000 0004 1936 8884Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON N6A 5B7 Canada
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Grieves LA, Gilles M, Cuthill IC, Székely T, MacDougall-Shackleton EA, Caspers BA. Olfactory camouflage and communication in birds. Biol Rev Camb Philos Soc 2022; 97:1193-1209. [PMID: 35128775 DOI: 10.1111/brv.12837] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 01/19/2022] [Accepted: 01/24/2022] [Indexed: 12/22/2022]
Abstract
Smell is a sensory modality that is rarely considered in birds, but evidence is mounting that olfaction is an important aspect of avian behaviour and ecology. The uropygial gland produces an odoriferous secretion (preen oil) that can differ seasonally and between the sexes. These differences are hypothesized to function in olfactory camouflage, i.e. minimizing detection by nest predators (olfactory crypsis hypothesis), and/or intraspecific olfactory communication, particularly during breeding (sex semiochemical hypothesis). However, evidence for seasonal and sex differences in preen oil is mixed, with some studies finding differences and others not, and direct evidence for the putative function(s) of seasonal variation and sex differences in preen oil remains limited. We conducted a systematic review of the evidence for such changes in preen oil chemical composition, finding seasonal differences in 95% of species (57/60 species in 35 studies) and sex differences in 47% of species (28/59 species in 46 studies). We then conducted phylogenetic comparative analyses using data from 59 bird species to evaluate evidence for both the olfactory crypsis and sex semiochemical hypotheses. Seasonal differences were more likely in the incubating than non-incubating sex in ground-nesting species, but were equally likely regardless of incubation strategy in non-ground-nesting species. This result supports the olfactory crypsis hypothesis, if ground nesters are more vulnerable to olfactorily searching predators than non-ground nesters. Sex differences were more likely in species with uniparental than biparental incubation and during breeding than non-breeding, consistent with both the olfactory crypsis and sex semiochemical hypotheses. At present, the data do not allow us to disentangle these two hypotheses, but we provide recommendations that will enable researchers to do so.
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Affiliation(s)
- Leanne A Grieves
- Department of Psychology, Neuroscience and Behaviour, McMaster University, Hamilton, Ontario, L8S 4M4, Canada
| | - Marc Gilles
- Department of Behavioural Ecology, Bielefeld University, Konsequenz 45, Bielefeld, 33615, Germany
| | - Innes C Cuthill
- School of Biological Sciences, Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, U.K
| | - Tamás Székely
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, U.K.,Department of Evolutionary Zoology and Human Biology, University of Debrecen, Egyetem ter 1, Debrecen, H-4032, Hungary
| | | | - Barbara A Caspers
- Department of Behavioural Ecology, Bielefeld University, Konsequenz 45, Bielefeld, 33615, Germany
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Bottini CLJ, MacDougall-Shackleton SA, Branfireun BA, Hobson KA. Feathers accurately reflect blood mercury at time of feather growth in a songbird. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 775:145739. [PMID: 33621875 DOI: 10.1016/j.scitotenv.2021.145739] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/04/2021] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
Methylmercury (MeHg) is a globally distributed pollutant that can negatively affect wildlife. Bird feathers are often used as a monitoring tool of contaminant exposure, but variability in total mercury (THg) content in flight feathers has raised concerns over their utility. The objective of this study was to quantify blood and feather THg depuration through the progression of primary feather molt in order to clarify the relationship between blood and feather mercury concentration, and test the reliability of feather THg measurements as a monitoring tool in wild songbirds. Song sparrows (Melospiza melodia) were experimentally exposed to dietary MeHg and their blood and primary feather THg concentrations were measured during exposure and post-exposure periods of three months each. A rapid decrease in feather and blood THg concentration through molt progression was observed. Primary feather THg content was higher in feathers grown during the MeHg exposure period compared to those grown during the post-exposure period. Primary feather THg concentration was highly correlated with blood THg measured at the time of feather growth (R = 0.98), indicating that, although THg concentration is variable among flight feathers, this reflects temporally sequential molting patterns and declining blood concentration during depuration. Primary flight feathers thus provide an accurate and useful tool for estimating the mercury burden of birds at the time a chosen feather was grown, and have the potential to be an effective and reliable biomonitoring tool for species with well-characterized molt patterns.
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Affiliation(s)
- Claire L J Bottini
- The University of Western Ontario, Department of Biology, 1151 Richmond St., London, Ontario N6A 5B7, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada.
| | - Scott A MacDougall-Shackleton
- Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada; The University of Western Ontario, Department of Psychology, 1151 Richmond St., London, Ontario, N6A 5C2, Canada
| | - Brian A Branfireun
- The University of Western Ontario, Department of Biology, 1151 Richmond St., London, Ontario N6A 5B7, Canada; Centre for Environment and Sustainability, University of Western Ontario, London, Ontario, Canada
| | - Keith A Hobson
- The University of Western Ontario, Department of Biology, 1151 Richmond St., London, Ontario N6A 5B7, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
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Individual Chemical Profiles in the Leach's Storm-Petrel. J Chem Ecol 2020; 46:845-864. [PMID: 32856136 DOI: 10.1007/s10886-020-01207-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 07/06/2020] [Accepted: 07/30/2020] [Indexed: 12/26/2022]
Abstract
Avian chemical communication, once largely overlooked, is a growing field that has revealed the important role that olfaction plays in the social lives of some birds. Leach's storm-petrels (Oceanodroma leucorhoa) have a remarkable sense of smell and a strong, musky scent. This long-lived, monogamous seabird relies on olfaction for nest relocation and foraging, but whether they use scent for communication is less well studied. They are nocturnally active at the breeding colony and yet successfully reunite with their mate despite poor night-vision, indicating an important role for non-visual communication. We investigated the chemical profiles of Leach's storm-petrels to determine whether there is socially relevant information encoded in their plumage odor. To capture the compounds comprising their strong scent, we developed a method to study the compounds present in the air surrounding their feathers using headspace stir bar sorptive extraction coupled with gas chromatography-mass spectrometry. We collected feathers from Leach's storm-petrels breeding on Bon Portage Island in Nova Scotia, Canada in both 2015 and 2016. Our method detected 142 commonly occurring compounds. We found interannual differences in chemical profiles between the two sampling years. Males and females had similar chemical profiles, while individuals had distinct chemical signatures across the two years. These findings suggest that the scent of the Leach's storm-petrel provides sociochemical information that could facilitate olfactory recognition of individuals and may inform mate choice decisions.
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