Nocturnal Variation in Body Temperature of Griffon Vultures

The diurnal cycle of metabolic rate (MR, J/g.h, based on Vo2 and Vco2) was measured in 14 Griffon Vultures (Gypsfulvus), two Hooded Vultures (Necrosyrtes monachus) and one White-backed Vulture (Gyps africanus) at different ambient temperatures (-7 to +34 °C).In (so far) three Griffon Vultures the heart rate (HR) and body temperature (Tb) were measured by telemetry, simultaneously with MR. The three vulture species show very similar physiological mechanisms. In all cases measured MR is significantly below allometrically expected values (G. fuh.,us -46 %, N. monachus -24 %, G. africanus -6 %). Fasting for 4 days results in an additional MR reduction of up to 27-35 %. There is a very small change of MR with ambient temperature (Ta). Therefore no obvious thermoneutral zone was observed in the broad Ta-range tested (see above). Ta-independent MR is the largest yet measured in birds. Thermal conductance (TC-wet) lies dramatically below expected values (-21.5 to -53.7 %), and is extensively used to control heat loss. All these special MR-strategies save energy expenditure. Tb of resting griffons shows a clear sinusoidal diurnal rhythm. The average Tb during the night has a mean value of 37.7 _+ 0.49 °C: the mean daytime value is 38.9 + 0.25 °C; the total average is 1,3/1.1 °C below expected values for Falconiformes, an effect significantly reducing energy expenditure. At Ta higher than about 25-30 °C, Tb increases significantly with increasing Ta, whereas MR does not vary significantly. Thus, the MR-independent variation of Tb may function as an additional and very effective mechanism for saving energy. Zusammenfassung Energieumsatz und K~rpertemperatur beim Giinsegeier (Gypsfulvus) mit vergleichenden Daten vom Kappengeier (Necrosyrtes monachus) und WeiBriicken-Geier (Gyps africanus)Der Tagesgang der Stoffwechselrate (MR, in J/g.h, basierend auf den] Sauerstoff-Verbrauch Vo2 und der Kohlendioxid-Abgabe Vco2) wurde bei 14 G~insegeiern (G3~sfidvus), zwei Kappengeiern (Necrosyrtes monachus) und einem Weif3rticken-Geier (Gyps @icanus) bei verschiedenen Umgebungstemperaturen (-7 bis +34 °C) bestimmt. Bei drei U.S. Copyright Clearance Center Code Statement: 0021-8375/2002/14304-0456 $ 15.00/0 R. Prinzinger et al. • Energy metabolism in vultures 457 Gfinsegeiern wurde fiber mehrere Wochen zus~itzlich die Herzschlagrate (HR) und die K6rpertemperatur (Tb) tiber Telemetrie simultan zur MR gemessen. Die drei Geierarten zeigen untereinander sehr/Jhnliche physiologische Regelmechanismen yon K~Srpertemperatur und Energieumsatz, Bei allen liegt die gemessene MR signifikant unter den allometrischen Erwartungswerten (G. fidvus -46 %, N. monachus -24 %, G. africanus -6 %). Schon viert/Jgiges Fasten ffihrt zu einer zus/itzlichen Stoffwechselreduktion von 27-35 %. Die Stoffwechselrate zeigt nut eine sehr geringe Abh/ingigkeit zur Umgebungstemperatur (Ta). Deshalb konnte im getesteten, weiten Ta-Bereich keine augenf/illige Thermoneutralzone bestimmt werden. Die Ta-unabh~ngige Stoffwechselrate ist auch die gr613te, die jemals bei V6geln best...

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“…This was also observed in the Griffon Vulture by Bahat et al (1998). This was also observed in the Griffon Vulture by Bahat et al (1998).…”

Section: Body Temperature Tb In the Griffon Vulturesupporting

confidence: 75%

“…Nine birds were tested in Israel (Bahat et al 1998), where they were housed in aviaries at the Zoological Gardens of Tel Aviv University (mean W 6.6 + t.0 kg: range 6.30-8.56 kg). First, 14 Griffon Vultures (Gyps filh'usl; no other published study is based on such a large number of tested individuals of the order Falconiformes.…”

Section: Tested Animalsmentioning

confidence: 99%

Energy metabolism and body temperature in the Griffon Vulture (Gyps fulvus) with comparative data on the Hooded Vulture (Necrosyrtes monachus) and the White-backed Vulture (Gyps africanus)

et al. 2002

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“…Also, eastern cliffs produce thermals quite early in the morning, as they are the first that receive the sunrays, thus facilitating the griffons to depart or raise their body temperature after a nocturnal drop during days of fasting (Bahat et al, 1998). Also, eastern cliffs produce thermals quite early in the morning, as they are the first that receive the sunrays, thus facilitating the griffons to depart or raise their body temperature after a nocturnal drop during days of fasting (Bahat et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

Griffon Vulture (Gyps Fulvus) Distribution and Density in Crete

Xirouchakis

Mylonas

2004

Israel Journal of Zoology

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Griffon vulture (Gyps fulvus) distribution and local density during 1996-2002 as well as the main characteristics of the species' activity sites in Crete are described. Total area of occurrence has been estimated at 7000 km 2 (85% of the island). 5500 km 2 (67%) accounted for its vital range, namely breeding and foraging, with spatial and temporal differences in correspondence to transhumant livestock. In total 68 activity sites were detected: (a) 34 colonies, of which 62% on average were occupied by laying pairs in any one year; (b) six deserted colonies; and (c) 17 summer and 11 winter roosts. Most of the sites were found in southwest and northeast Crete on rocks of calcareous substrate. The species nesting and roosting sites were found on dolomitic and platy limestone cliffs, respectively. Mean altitude of activity sites was 650 m (SD = 442 m, range = 120-1900 m), whereas mean altitude of active colonies was 453 m (SD = 225 m, range = 120-1100 m). Cliffs were on average 182 m high (range = 40-540 m) facing southeast with a significant directionality for active colonies (southeast) and summer roosts (northwest). The distribution of activity sites was clumped, while the nearest neighboring distance was 6.2 km (range = 900 m-22.5 km). The spacing of active colonies was random with a tendency towards aggregation. The mean nearest distance between active colonies was 11 km (range = 9.1-13.3 km) and their average density for the species vital range was one active colony per 262 km 2 . The latter figure implied that each breeding group had a foraging range at a radius of ca. 9 km from the colony's cliff. S.M. XIROUCHAKIS AND M. MYLONAS Isr. J. Zool.

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“…Endotherms have also evolved physiological mechanisms that allow them to depress their otherwise high metabolic rates at certain times. For example, vultures who do so while resting at their roost and during periods of food deprivation, a problem that their large body size also helps to overcome (Bahat et al , Moleón et al ).…”

Section: The Challenges Of Scavengingmentioning

confidence: 99%

A recipe for scavenging in vertebrates – the natural history of a behaviour

et al. 2016

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Despite its prevalence, the importance of scavenging to carnivores is difficult to ascertain in modern day forms and impossible to study directly in extinct species. Yet, there are certain intrinsic and environmental features of a species that push it towards a scavenging lifestyle. These can be thought of as some of the principal parameters in optimal foraging theory namely, encounter rate and handling time. We use these components to highlight the morphologies and environments that would have been conducive to scavenging over geological time by focusing on the dominant vertebrate groups of the land, sea and air. The result is a synthesis on the natural history of scavenging. The features that make up our qualitative scale of scavenging can be applied to any given species and allow us to judge the likely importance of this foraging behaviour

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Nocturnal Variation in Body Temperature of Griffon Vultures

Cited by 17 publications

References 14 publications

Energy metabolism and body temperature in the Griffon Vulture (Gyps fulvus) with comparative data on the Hooded Vulture (Necrosyrtes monachus) and the White-backed Vulture (Gyps africanus)

Energy metabolism and body temperature in the Griffon Vulture (Gyps fulvus) with comparative data on the Hooded Vulture (Necrosyrtes monachus) and the White-backed Vulture (Gyps africanus)

Griffon Vulture (Gyps Fulvus) Distribution and Density in Crete

A recipe for scavenging in vertebrates – the natural history of a behaviour

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