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Eurasian Griffon Gyps fulvus Scientific name definitions

Alfredo Salvador
Version: 6.0 — Published July 26, 2024

Breeding

Introduction

The Eurasian Griffon has a prolonged breeding season, probably as an adaptation to the unpredictable availability of carrion during reproduction. It usually nests on cliffs, rarely in trees or mounds. Aerial displays occur from mid-September to mid-December. Both sexes contribute to the construction and maintenance of the nest. A single brood of one egg (rarely two) is laid between November and mid-April, although replacement clutches can occur. The male and female take turns incubating the eggs while the other forages. The incubation period lasts 49–65 d. Hatching occurs from mid-February through April, and fledging between early June and end of August, at 97–136 d after hatching. The immature stage ranges from one to four years.

Phenology

Pair Formation

In Crete (Greece), aerial displays increased from mid-September through mid-December (344).

First Brood

The early start of the breeding season may be timed to take advantage of seasonal thermals for activities with high energy demands, such as the feeding and flight training of fledglings (247). The start of the breeding season varies with latitude. Laying takes place between November and February in the Middle East, between December and March in southern Europe, between February and April in northwest Africa, between March and April in the Caucasus, between 25 December and 16 April in Crete (390, 391), between the end of February and 10 March in Turkmenistan (340), and and between late January and late March in Uzbekistan (237). In Gipuzkoa Province (northern Spain), laying takes place between the second week of January and the second week of February (392), and in southern Spain, laying occurs between 20 December and 10 February (393). In Baluchistan (Pakistan), subspecies fulvescens lays between November and February (156, 9). Older females lay earlier than younger females (179).

Hatching in Crete occurred between 15 February and 29 April, and fledging between 4 June and 23 August (391). In the Kvarner Islands (Croatia), eggs hatched between 3 February and 29 April (85).

Second/Later Broods

The Eurasian Griffon typically lays only one clutch. However, a second clutch may be laid if the first is lost. Captive birds in Israel laid a second egg an average of 28.5 d (range 25–32 d) after losing the first egg (364). Replacement clutches in the wild were recorded in Cádiz (Spain; 206); a freshly laid egg was removed from two nests, and the females laid again after 20 and 28 d, respectively (348). In Crete (Greece), 1.2% of failed first clutches (n = 252) were replaced after 25–35 d, and failed again (391).

Between 1991–1997, breeding failures and replacement clutches were studied in a colony at Hoces del Riaza Natural Reserve (Segovia, Spain). Of the 533 pairs that experienced breeding failure, 3.8% of them on average laid replacement clutches and renested, and there was no significant difference in the number of pairs that renested in different years (range 2.4–5.9%, n = 5 years). Renesting occurred an estimated 25 d after failure; 15% of the replacement clutches were successful, with three nestlings fledging between September and October (394). In the Western Pyrenees (France), the proportion of replacement clutches was 2.7% (395). In contrast, from 1982–1992 in the Grands Causses (France), 39% of a reintroduced population laid a replacement clutch when an egg was lost during incubation. For failure occurring early in the nestling stage, only one replacement clutch was recorded (n = 5; 238).

Nest Site

Microhabitat and Site Characteristics

The Eurasian Griffon usually nests on cliffs, rarely in trees (179, 9, 3), or on mounds (156). In Crete (Greece), it preferred to nest on high limestone cliffs located at mid-elevations above sea level, with protection from prevailing winds and access to livestock (396). Nesting sites in the Caucasus were negatively correlated with annual rainfall and positively correlated with the percentage of open areas within a 20-km radius surrounding the cliff (194). Nesting sites in Castellón (Spain) were associated with larger cliffs, higher elevations, and forest coverage in the surrounding landscape (397). In Cyprus, nests were found on cliffs at a mean height of 29 m; nests were built in small caves (77.1%) and ledges (22.9%, n = 36 nests) (185). In Herzegovina (Bosnia and Herzegovina), most nests were located in caves (31%) or half-caves (36.1%), and at a mean height of 60 m from the bottom of the cliff (range 3–181 m, n = 61 nests) (202). Nests have also been recorded on mounds in the Karakum Desert, Turkmenistan (156).

Environmental conditions of nesting sites can influence reproductive success. In Castellón (Spain), nests were located on open ledges (55%), sheltered ledges (26%), and caves (19%), and were mostly oriented to the south (33.3%) and southwest (25.25%) (n = 100) (398). Nests located in caves or facing south had greater reproductive success (398, 239). In a study from Guipúzcoa (Spain), the mean number of nestlings and fledglings was higher in nests located on ledges with an overhang than in nests located on uncovered platforms and ledges (392). At some sites, parents shaded nestlings to prevent them from overheating (344, 377); parents at exposed nests that invest more time in brooding or shading the nestling suffer a cost of lower breeding success (239). However, similar conditions are not always associated with nest success; in Hoces del Riaza Natural Reserve (Segovia, Spain), a long term study (1992–2011) that measured nest quality (the total number of fledglings produced in each nest) revealed that productivity was not linked to either sunlight exposure or nest orientation (18).

In Castellón (Spain), a significantly negative relationship was found between nest success and the distance to the nearest nest in the colony. The cause of this correlation is unknown, but it could be related to the risk of predation by Common Raven (Corvus corax). It could be more difficult for the Common Raven to predate nests which are closer to others (398).

In areas where cliffs were scarce, Eurasian Griffon used nests in trees built by Cinereous Vulture (Aegypius monachus), White-tailed Eagle (Haliaeetus albicilla), and Imperial Eagle (Aquila heliaca) (179). Nests in trees have been documented in the Dobrogea Region (Romania), the Fruska Gora Mountains (Serbia), and the Sierra Morena Mountains (Spain) (9, 399). In southeastern Madrid (Spain), nests used by Eurasian Griffon but built by Cinereous Vulture in trees were mainly placed in Pinus pinaster (400). Prevalence of haemosporidian parasites of the Leucocytozoon lineage CIAE02 was significantly higher in nestlings from tree nests (n = 9) than in those from cliff nests (n = 119) (401).

Nest

Construction Process

Both sexes contributed to the construction and care of the nest (272). Materials for the nest were carried in the beak from nearby areas (348), typically within 2.5 km of the nest (344). The theft of nest material was not uncommon, and birds also collected branches from abandoned nests on the same cliff (344).

In Crete (Greece), it began nest construction by bringing material (branches and leaves, often from aromatic plants) in December, on average 32 d ± 9 SD before laying (range 17–44 d, n = 141). Material was brought, on average, five times a day (± 3.5 SD, range 4–14, n = 52), increasing in January to seven times a day (± 2.36 SD, range 4–14, n = 52). An adult always remained on the nest during construction, and most nest construction took place during the morning and midday hours. Males collected and contributed significantly more nesting materials than females (n = 6 pairs), while the female or both members of the pair arranged the nest material. The mean number of items transported to the nest per trip was 2 ± 1.3 SD (range 1–8), and on average 320 items were supplied to the nest (344).

Structure and Composition

The nest can be constructed using a variety of materials: twigs, wild vines, dry stalks, hay, or just a shallow hollow in the ground covered with green pine twigs. Occasionally the nest comprised only a few knots, pieces of dwarf palm leaf, and some grass (9). In Crete (Greece), the nest was constructed of dry branches, sticks, dry and fresh grasses, and a nest lining of fresh plants. Plant species represented were Genista acanthoclada, Ceratonia siliqua, Quercus coccifera, Euphorbia dendroides, Pistacia lentiscus, Pinus brutia, Olea europea, Drimia maritima, Pteridium aquilinum, Phlomis fruticosa, Salvia fruticosa, and unidentified grasses (Poaceae; 344). In Cádiz (Spain), the nests were built using branches of Olea europaea, Ceratonia siliqua, and Pistacia lentiscus, covered with herbs, leaves, down feathers, and hair in some nests (348). In the central Kopet Dag Mountains (Turkmenistan), nest materials included the dried twigs and bark of Juniperus turcomanica and dried wormwood (321). In southwestern Türkiye, nests were constructed with twigs of pines (Pinus nigra), and one Eurasian Griffon was observed carrying mistletoe (Viscum album; 402).

Dimensions

In Cádiz (Spain), the outside diameter of nests averaged 65.3 cm (range 50–84 cm), with a mean height of 15 cm, and an inside depth of 7–12.5 cm (n = 156; 348). In Armenia, the outer diameter averaged 67.5 x 91.5 cm, the inner diameter 35.5 x 40.5 cm, and the cup depth 7.25 cm (n = 6; 403).

Eggs

Shape

Egg shape has been described as rounded elliptical to broad oval, seldom longer (9), as well as broad ovate (3).

Size

In nominate fulvus, across multiple populations, mean egg size was 92.4 x 69.7 mm (range 82–106 x 64–75, n = 100; 404). Across different studies, egg size did not vary much. In Spain, different studies found mean egg size was 92.0 x 70.1 mm (range 81.5–101.2 x 64.5–75.0, n = 60; 9) and 89.9 x 68.1 mm (range 82.6–93.4 x 66.5–70.2, n = 137; 348), while in a study combining measurements from Spain and Algeria, mean egg size was 92.01 x 70.1 mm (n = 59; 42). In the Balkans (southeastern Europe), mean egg size was 92.9 x 69.0 mm (range 85.3–97.6 x 66.5–73.8, n = 14; 9), and in Romania it was 92.3 x 69.1 mm (n = 19; 179).

In subspecies fulvescens, across multiple populations, mean egg size was 90.7 x 70.2 mm (range 83.8–97.0 x 65.0–73.3, n = 25; 404).

Mass

In Cádiz (Spain), mean egg mass was 227.6 g (range 218–241, n = 127; 348). In Nurata Nature Reserve (Uzbekistan), mean egg mass was 254.1 g (range 206.5–292, n = 4; 237).

Eggshell Thickness

Mean thickness of eggshell in Cádiz (Spain) was 0.692 mm (n = 29; 348).

Color and Surface Texture

Eggs have a smooth shell (3). They are mostly plain white, and less commonly with a number of scattered or clustered small rust-brown spots at one end. Heavily marked eggs with lilac spots are very rare (9).

Clutch Size

Typically one egg, rarely two (9). A nest with one egg and a nestling was observed in Algeria (405), and nests with two eggs have been recorded in Navarra (Spain; 406), Israel (407), Grands Causses (France; 238, 408), Sardinia (Italy; 409), and Sicily (Italy; 410). It has been suggested that clutches of two eggs were almost certainly laid by two females (411), but no supporting information was provided.

There is scarce information on fledging success in nests with two eggs. In the reintroduced population in Grands Causses (France), one pair of released adults laid clutches of two eggs every year over four years, but only fledged one chick (238). In Sicily (Italy), one nest had two eggs and both fledged (410).

Incubation

Incubation Period

In Crete (Greece), mean incubation duration from 1997–2001 was 57 d ± 4 SD (range 49–65, n = 101; 391).

The rate of embryonic oxygen consumption (MO2) in Eurasian Griffon eggs plateaued from about day 47 to day 54, just prior to the start of external pipping (412).

Parental Behavior

The male and female of a pair take turns incubating while the other forages. The transition between incubation shifts, marked by the arrival of one member and the departure of the incubating adult, lasted 12 s ± 5 SD (range 3–480 s, n = 54) in one study (344). Incubation shifts observed over four days lasted on average 37.4 h ± 0.5 SD (range 25.6–50.2, n = 3 pairs; 344). Breaks during incubation ranged from 20 s to 10 min (413). Long incubation interruptions (0.5–2.0 h) were recorded in Crete (Greece) in February and March during days when the ambient temperature reached >30° C at midday (391).

According to observations made on 45 breeding pairs in southern Spain, during the first 3–5 d, the female takes charge of incubation; during daytime, the male incubates on average 12.6% during the first 10 d, 22.7% during days 11–25 of incubation, 42.8% during days 26–50, and it drops to 10.5% from day 51 until hatching (301). On average, captive males in Israel incubated 57.5% (range 19.8–62.9%) of the total incubation time, and the captive females 42.5% (range 37.1–80.2%; 364).

Hatching

Shell Breaking and Emergence

Hatching duration in captivity in Israel lasted 1–4 d from the first pipping of the egg to the emergence of the chick (364).

Parental Assistance and Disposal of Eggshells

In some cases, the incubating adult was observed nibbling at the opening of the egg and breaking off pieces of the eggshell (364).

Young Birds

Condition at Hatching

Hatchlings are semi-altricial and nidicolous (3), and have a mass of 170–210 g (17).

Growth and Development

At hatching, the hallux is in the closed position and opens between days 47 and 52 (16).

The correlation of the length of ruff feathers at the base of lower hindneck and age were examined in Cádiz (Spain): for lengths of 14–17 mm, 23–26 mm, 26–29 mm, 30–35 mm, 35–42 mm, 60–65 mm, 67–72 mm, and 78–89 mm, the age was 25–32 d, 32–42 d, 42–52 d, 50–60 d, 60–70 d, 70–80 d, 80-90 d, and 90+ d, respectively (348).

In Armenia, mass of a chick was tracked: 873 g at 14 d, 2,300 g at 29–30 d, 5,100–6,250 g at 50–54 d, and 8,200–8,600 g at 100 d. Mass of another nestling was 2,200 g at 32 d, 6,000 g at 76 d, 6,550 g at 100 d, and 7,550 at 120 d. Mean mass of nestlings was 5,773 g at 80–85 d, 7,075 g at 90–95 d, and 7,800 g at 105–110 d (317).

Parental Care

Brooding

Nest attendance by the breeding pair varies with nestling age. In one study, during the first five days of the nestling's life, the female stayed at the nest constantly to brood the chick (301). In other studies, during the first 3–4 weeks of the nestlings' life (414), one adult was always present (344). On sunny days, adult vultures often covered nestlings as protection from the sun (344, 377). At 6–7 weeks, the nestling was alone for mean periods of 30 min ± 8 SD (range 12–43 min, n = 18), increasing to 62 min ± 24 SD (range 34–160 min, n = 18) when 10–12 weeks old. Nestlings were left alone during the morning and midday hours once they reached three months of age (344).

Observations carried out on 45 breeding pairs in southern Spain showed that during the first five days of the nestling's life, on average, males remain in the nest 37% of the time during daylight hours; during days 6–25 after hatching, the male remains in the nest for 15.9% and the female for 76% of the time, with the nestling remaining alone for 8.1% of the time; during days 26–50 of age, the male stayed in the nest for 30%, the female for 40%, and the nestling was alone for 30% of the time; beginning at day 51 of age, each adult was in the nest 25% of daylight hours, and the nestling was alone the rest of the time (301).

Asymmetry in parental roles during chick rearing can also occur. In one study from Israel of nine breeding events that lead to successful fledging, the mean proportion of time at the nest in males and females was 0.484 ± 0.039 SE and 0.334 ± 0.025 SE, respectively. The asymmetry in the proportion of time spent at the nest was 0.367 ± 0.070 SE and was significantly different from zero (P = 0.002; 415). Higher investment in presence at the nest by males could be related to their larger head and bill size than females (35), an important trait to be used in nest defense (415).

Adults also frequently preened the nestling, sometime spending 50% of the day in the activity (364).

Feeding

In one study, during its first few days after hatching, a parent provided the nestling with partially digested food, transferred from the tip of the parent's bill to the tip of the chick's bill. After a week, the adult regurgitated meat into its mouth, which it then presented to the nestling with an open bill, and the nestling pecked inside (364).

According to observations made in Crete (Greece), during the nestling's first seven weeks, adults transferred food to the nestling's bill or regurgitated into the nest for the nestling; sometimes the nestlings received water. At eight weeks and onward, the nestling pecked the parent's beak to induce regurgitation and took food directly from the parent's beak. The observed feeding rate was 1 ± 1.25 bouts per day (range 1–4, n = 26 pair/days) over the entire breeding period. On days when no feeding was observed, parents visited the nest an average 2.9 times per day (range 1–8, n = 26). At ten weeks after hatching, both parents foraged and feeding rates increased to 1.5 ± 0.74 bouts per day (range 1–3, n = 23); from 12 weeks after hatching, the mean number of bouts per day was 2.5 ± 1.29 SD (range 1–4, n = 27). The mean of 2.9 visits per day even when no food was delivered was not significantly different from days when food was delivered, however days of successful foraging did see almost double the number of visits. Feeding the nestling lasted on average 2.6 min ± 2.36 SD (range 2–15, n = 66) per visit. Nestlings received an estimated 600 g of food per day (344).

Food provisioning to the nestling is done by both parents, but there is variation between sexes that is poorly known. The mean feeding rates of males and females was 0.100 bouts/h ± 0.005 SE and 0.072 bouts/h ± 0.010 SE, respectively, in a study of nine breeding events in Israel. The mean asymmetry in the feeding rate was 0.336 ± 0.135 SE, and was significantly different from zero (P = 0.047; 415). Higher food provisioning rates of males could be related to higher flying performance due to their smaller wing load in comparison with females (35, 415). In Spain, a breeding male was absent for 40 d during the period of food provisioning to the nestling (4 June–14 July), and during that time interval the female took care of all the reproductive tasks; the male returned to the nest 21 d after the nestling fledged (416).

Cooperative Breeding

Information needed.

Brood Parasitism by Other Species

Information needed.

Fledgling Stage

Departure from the Nest

In Crete (Greece), mean age of fledging was reported as 117 d ± 10 SD (range 102–134, n = 12; 344) and 120 d ± 9 SD (range 97–136, n = 89; 391) in two different studies. No significant variation between years in fledging dates was observed (n = 5 years).

Association with Parents or Other Young

Some fledglings were observed receiving food from their parents for 68 d after leaving the nest (391).

Immature Stage

The immature stage generally lasts 4–5 years (238). Eurasian Griffon banded as nestlings in Biscay (Spain) were later observed in their natal area after an average hiatus of 3.23 years ± 1.01 SD (range 2–6, n = 13; 302). During the elapsed period, juveniles wandered throughout the Iberian Peninsula (302).

Recommended Citation

Salvador, A. (2024). Eurasian Griffon (Gyps fulvus), version 6.0. In Birds of the World (S. M. Billerman and M. A. Bridwell, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.eurgri1.06
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