BIJLSMA RG (1999) Do Honey Buzzards Pernis apivorus produce pellets?. LIMOSA 72 (3): 99-103.

During 1971-98 247 nests of Honey Buzzards on the Ve1uwe and in western Drenthe were climbed and controlled during egg (208 times) and nestling stage (549 times). During these 757 nest visits, pellets were never found. This lack of pellets conflicted with statements in the literature, which - on closer examination - failed to provide convincing data. Alleged pellets turned out to have been droppings, which mainly consist of indigestible residues of wasps and other insects and comb fragments. Such droppings are deposited on the nest rim where they may form pellet-like debris.
      Pellet production was tested in two semi-captive Honey Buzzards which were held on a diet of Wood Mice Apodemus sylvaticus and bananas. Both birds were closely observed in a cage (for 153 hours on 18 days) and after their release (for 557 hours on 56 days). The juvenile of 1997 received 59 mice (and lots of bananas) from 3 September through its departure on 26 September. It was unable to forage independently because of extreme wasp scarcity in 1997. This bird produced at least four small pellets consisting entirely of hair of mice (no bones), one of which measured 31x12 mm. A second calender- year female received 22 mice (and bananas) from 22 July till 8 August 1998. It was radio-tagged and released on 2 August, and became fully independent from 9 August onwards. During captivity, it never produced a pellet (despite its forced diet of mice) nor were any pellets found beneath its sitting and sleeping posts in the wild. On 27 August, when already on a diet of wasp larvae for more than two weeks, it spontaneously produced a watery pellet, the only pellet known from this bird between 22 July and its departure on 10 September. Both birds were regularly eating downy feathers, but its use in pellet formation is questionable (too few, mainly down).
      Although Honey Buzzards are able to produce pellets, this is clearly a rare event in the wild, since mammals are hardly ever taken (only six mammals on thousands of prey remains in.my study areas). Moreover, Honey Buzzards are very particular when eating vertebrate prey, discarding large bones, skin, feathers and hair as much Limosa 72 (1999) 3 as possible. The four pellets produced by the captive juvenile were based on a forced diet of mice, a very unlikely diet of free-living Honey Buzzards, even when experiencing severe wasp scarcity.

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