Dietary exposure to methylmercury affects flight endurance in a migratory songbird

Ma, Yanju; Perez, Cristina R.; Branfireun, Brian A.; Guglielmo, Christopher G.

doi:10.1016/j.envpol.2017.12.011

Cited by 37 publications

(28 citation statements)

References 60 publications

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“…We also did not find a significant treatment effect for either measure of flight energy expenditure. In other words, the finding of low exercise performance in anti-EPO-treated birds was made based only on the number of strikes in the first 30 min of flight but this metric has been proven to be a valid measurement of flight performance in other wind tunnel studies (Ma et al, 2018;Maggini et al, 2017). As discussed before, migratory endurance flight is an energetically demanding activity (Piersma, 2011) and, thus, high oxygen carrying capacity is essential for maintenance of the intense exercise.…”

Section: Discussionmentioning

confidence: 99%

“…It is capable of simulating high-altitude conditions with low-turbulence air flow at various speeds. It has been used routinely to study flight in birds, and birds do exhibit natural flight behavior in the tunnel (Ma et al, 2018;Maggini et al, 2017). To familiarize birds with the wind tunnel and to screen for birds that would fly voluntarily and reliably for long periods in the wind tunnel, individuals were flown at 15°C, 70% relative humidity and at speeds between 7 and 8 m s −1 2 weeks prior to the start of the experiment (i.e.…”

Section: Hypobaric Climatic Wind Tunnel and Screeningmentioning

confidence: 99%

“…We also calculated both cost of transport [COT=E/(wind speed×flight duration)] and flight power (E/flight duration). We chose to assess the number of strikes in the first 30 min of flight because it has been shown that the first 30 min are the most challenging time as birds adjust to conditions in the wind tunnel (Ma et al, 2018), possibly because birds make a suite of physiological adjustments during the onset of flight (Gerson and Guglielmo, 2013;Jenni et al, 2006). For posttreatment flights, in addition to the four performance metrics above, we also included three other performance metrics: (1) altitude (the maximum altitude attained by the bird at the end of the flight test period, or the altitude at which the bird failed to maintain continuous flight for 1 min), (2) altitude duration (the total duration of flight at 3000 m) and (3) altitude strikes (the number of strikes at 3000 m).…”

Section: Behavioural Observations and Determination Of Flight Performmentioning

confidence: 99%

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Effects of experimental manipulation of hematocrit on avian flight performance in high and low altitude conditions

Yap

Dick

Guglielmo

et al. 2018

Journal of Experimental Biology

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Despite widely held assumptions that hematocrit (Hct) is a key determinant of aerobic capacity and exercise performance, this relationship has not often been tested rigorously in birds and results to date are mixed. Migration in birds involves high-intensity exercise for long durations at various altitudes. Therefore, it provides a good model system to examine the effect of Hct on flight performance and physiological responses of exercise at high altitude. We treated yellow-rumped warblers (Setophaga coronata) with avian erythropoietin (EPO) and anti-EPO to experimentally manipulate Hct and assessed flight performance at low and high altitudes using a hypobaric wind tunnel. We showed that anti-EPOtreated birds had lower Hct than vehicle-and EPO-treated birds posttreatment. Anti-EPO-treated birds also had marginally lower exercise performance at low altitude, committing a higher number of strikes (mistakes) in the first 30 min of flight. However, anti-EPO-treated birds performed significantly better at high altitude, attaining a higher altitude in a ramped altitude challenge to 3000 m equivalent altitude, and with a longer duration of flight at high altitude. Birds exercising at high altitude showed decreased Hct, increased glucose mobilization and decreased antioxidant capacity, regardless of treatment. In summary, we provide experimental evidence that the relationship between Hct and exercise performance is dependent on altitude. Future studies should investigate whether free-living birds adaptively modulate their Hct, potentially through a combination of erythropoiesis and plasma volume regulation (i.e. hemodilution), based on the altitude they fly at during migratory flight.

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Section: Discussionmentioning

confidence: 99%

Section: Hypobaric Climatic Wind Tunnel and Screeningmentioning

confidence: 99%

Section: Behavioural Observations and Determination Of Flight Performmentioning

confidence: 99%

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Effects of experimental manipulation of hematocrit on avian flight performance in high and low altitude conditions

Yap

Dick

Guglielmo

et al. 2018

Journal of Experimental Biology

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“…The blackpoll warbler is an exceptional migrant that undertakes non-stop, multi-day flights over the Atlantic Ocean to reach wintering areas in South America (DeLuca et al 2015). As a neurotoxin, Hg may impair their navigation (Moye et al 2016), flight performance (Ma et al 2018), and foraging ability (Kobiela et al 2015). Thus, it is reasonable to posit that Hg burden may contribute to reduced survival during migration and winter for this species.…”

Section: Seasonal Effects Of Mercury On Long-distance Migratory Insecmentioning

confidence: 99%

“…Methylmercury has been demonstrated to impair bird immune function (Hawley et al 2009, Lewis et al 2013), foraging behavior (Kobiela et al 2015), navigation (Moye et al 2016), and flight ability (Carlson et al 2014, Ma et al 2018, which could be particularly detrimental during long-distance migration. In this study, we used songbird feathers grown prior to autumn migration to examine the link between Hg exposure at breeding grounds and songbird survival until the subsequent spring return migration (a seasonal carry-over effect).…”

Section: Introductionmentioning

confidence: 99%

Evidence of negative seasonal carry‐over effects of breeding ground mercury exposure on survival of migratory songbirds

Branfireun

Hobson

et al. 2018

Journal of Avian Biology

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Mercury (Hg) is a well‐known global contaminant that persists in the environment. The organic form, methylmercury (MeHg) has been shown to adversely affect bird immune function, foraging behavior, navigation, and flight ability, which individually or together could reduce migration performance, and ultimately survival. Nestlings grow feathers at their natal site, and in North America many adult passerines undergo a complete feather molt prior to autumn migration at or near their breeding location. Body Hg is redistributed into growing feathers, and remains stable following feather growth. As flight feathers are retained in most species over the non‐breeding season until molt in the following summer, tail feathers can be used at other times and places as indicators of Hg body burden on the breeding grounds. In five migratory passerine species, we compared Hg concentrations in tail feathers that were grown prior to autumn migration and retained until the following spring. We predicted that we would observe a shift in the distribution of species‐specific feather Hg values towards lower means in the spring if Hg reduced survival over the migration and winter periods. We found reductions in mean feather Hg between autumn and spring in two long‐distance migratory insectivores (blackpoll warbler Setophaga striata; American redstart Setophaga ruticilla). Most significantly, spring‐returning blackpoll warblers, a species that undertakes long non‐stop flights to South America during autumn migration, had nearly 50 percent lower Hg concentrations than those that departed in the autumn. Our finding suggests that Hg exposure on the breeding areas could have a carry‐over effect to influence migration success and survival of insectivorous songbirds that undergo extensive and demanding migratory journeys. More investigation is needed to fully understand the relationships among Hg exposure, migration performance, and survival of songbirds.

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Green Kingfishers as Sentinel Species for Mercury Contamination in Amazon

Oliveira

Ignácio

Lázaro

et al. 2023

Arch Environ Contam Toxicol

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Mercury is a global contaminant naturally found in the Amazon; it can be biomagni ed in the aquatic trophic chain. The use of piscivorous avians for mercurial contamination biomonitoring is increasing, mainly due to the non-mobility of mercury in avian feathers. We examined the concentrations of total mercury and methylmercury in different Chloroceryle americana tissues from the Teles Pires and Juruena Rivers in the southern Brazilian Amazon. We also evaluated total mercury in small Characidae sh (potential C. americana food) in the same areas. The results evidenced high mercury concentrations, on average two-times higher in the green king shers from the Teles Pires River compared to the Juruena River; the same results were found for the sh specimens. Mercury concentrations were lowest in the muscle, followed by liver and highest in feathers. Fifty-eight per cent of the feather samples from the Juruena River and 90% from the Teles Pires River had total mercury concentrations above 5 µg/g, a level previously associated with adverse effects related to avian breeding. The methylmercury concentration was lowest in the liver, followed by feathers and highest in muscle. Although Juruena River avian feathers had a lower total mercury concentration, > 96% of the total mercury was methylmercury, the highest amount for specimens from both rivers. Highlights 1-Hg concentrations in King shers exceed the limits established by FAO; 2-Bird feathers can be considered a good indicator of mercury contamination; 3-The percentage of MeHg present in the feathers and liver shows the e ciency of the Hg excretion routes in C. americana.

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Dietary exposure to methylmercury affects flight endurance in a migratory songbird

Cited by 37 publications

References 60 publications

Effects of experimental manipulation of hematocrit on avian flight performance in high and low altitude conditions

Effects of experimental manipulation of hematocrit on avian flight performance in high and low altitude conditions

Evidence of negative seasonal carry‐over effects of breeding ground mercury exposure on survival of migratory songbirds

Green Kingfishers as Sentinel Species for Mercury Contamination in Amazon

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