Bone composition and bone mineral density of long bones of free-living raptors

Abstract

Bone composition and bone mineral density (BMD) of long bones of two raptor and one owl species were assessed. Right humerus and tibiotarsus of 40 common buzzards, 13 white-tailed sea eagles and 9 barn owls were analyzed. Statistical analysis was performed for influence of species, age, gender and nutritional status. The BMD ranged from 1.8 g/cm3 (common buzzards) to 2.0 g/cm3 (white-tailed sea eagles). Dry matter was 87.0% (buzzards) to 89.5% (sea eagles). Percentage of bone ash was lower in sea eagles than in buzzards and owls. Content of crude fat was lower than 2% of the dry matter in all bones. In humeri lower calcium values (220 g/kg fat free dry matter) were detected in sea eagles than in barn owls (246 g/kg), in tibiotarsi no species differences were observed. Phosphorus levels were lowest in sea eagles (humeri 104 g/kg fat free dry matter, tibiotarsi 102 g/kg) and highest in barn owls. Calcium-phosphorus ratio was about 2:1 in all species. Magnesium content was lower in sea eagles (humeri 2590 mg/kg fat free dry matter, tibiotarsi 2510 mg/kg) than in buzzards and owls. Bones of barn owls contained more copper (humeri 8.7 mg/kg fat free dry matter, tibiotarsi 12.7 mg/kg) than in the Accipitridae. Zinc content was highest in sea eagles (humeri 278 mg/kg fat free dry matter, tibiotarsi 273 mg/kg) and lowest in barn owls (humeri 185 mg/kg, tibiotarsi 199 mg/kg). The present study shows that bone characteristics can be considered as species specific in raptors.

Diagenesis of archaeological bone and tooth

“…Some highly specialized bony elements such as the bulla tympanum and rostrum of whales are almost totally mineralized with only 11 %, and <1% collagen, respectively (Zioupos et al, 2000) . Bird bones are stronger and have higher densities (Dumont, 2010) but it is unclear whether this truly reflects a higher proportion of mineral or simply a lower porosity (Schuhmann et al, 2014) . Amongst humans, the highly mineralised petrous portion of the temporal bone is attracting attention due to the often high levels of protein and endogenous DNA that can survive in archaeological specimens compared to non-petrous skeletal elements (Gamba et al, 2014;Jørkov et al, 2009) .…”

Profile of Selected Mineral Elements in Tibiotarsal Bone of the White-Tailed Sea Eagle in Its Natural Habitat

“…The bone tissue that builds the skeleton of a bird consists of both organic and inorganic components. Previous studies described levels of dry matter, ash in dry matter, and other elements in the bones of many bird species, including poultry, psittacines, and some raptor species [ 12 ]. According to the literature data, in poultry, dry matter ranges from 45% to 88%, while in White-Tailed Sea Eagles from 80.5% to 91.2% (studies were carried out on 13 eagles) [ 12 ].…”

“…Previous studies described levels of dry matter, ash in dry matter, and other elements in the bones of many bird species, including poultry, psittacines, and some raptor species [ 12 ]. According to the literature data, in poultry, dry matter ranges from 45% to 88%, while in White-Tailed Sea Eagles from 80.5% to 91.2% (studies were carried out on 13 eagles) [ 12 ]. The skeleton consists mainly of calcium and phosphorus in a ratio of 2:1, and the calcium content of the bones increases with age in poultry.…”

“…In different bird species the ratio ranges from 1.9:1, in poultry and various psittacines, to 2.5:1, in budgerigars. In birds of prey, as a single paper shows, calcium contents in a single buzzard and a single falcon are 325 g/kg and 329 g/kg, respectively [ 12 ]. About 60% of the total magnesium amount in the body is stored in the bones.…”

“…About 60% of the total magnesium amount in the body is stored in the bones. In one study with raptor species, the levels were 4700 mg/kg ash magnesium in one falcon and 6100 mg/kg ash magnesium in one buzzard, which is higher than median magnesium levels in other described bird species [ 12 ].…”