A short note on an analysis of Little Eagle pellets 

An adult female Little Eagle eating a rosella provided to her by her mate.

A short article has been recently published in Canberra Bird Notes, describing a sample of food items in Little Eagle pellets in the ACT area. The main prey items were rabbit and small-medium sized birds and smaller number of lizards.

Rae, S., Davies, M., Mulvaney, M., Fletcher, D., Kiggins, R., Stol, J., Roberts, D., and Olsen, P. (2021). Prey items identified from Little Eagle pellets collected in and around the Australian Capital Territory. Canberra Bird Notes 46: 64-69.

Abstract: We describe the prey items identified in 810 food pellets ejected by Little Eagles (Hieraaetus morphnoides) in the ACT and nearby NSW. European Rabbit (Oryctolagus cuniculus) was the most frequent prey species, found in 87% of pellets. The remains of birds were in 31% and reptile remains were in 13%. The most frequent birds eaten were Eastern and Crimson Rosellas (Platycercus eximius and P. elegans), and European Starling (Sturnus vulgaris). The reptiles were all lizards, and the most frequent remains were of Eastern Blue-tongue (Tiliqua scincoides scincoides), dragon sp. and skink sp. Miscellaneous items included, Black Rat (Rattus rattus), Red Fox (Vulpes vulpes), Eastern Grey Kangaroo (Macropus giganteus) and sheep (Ovis aries). Traces of insects eaten were scarce (in 1.8% of pellets) and all were either beetles (Coleoptera) or grasshoppers (Caelifera). The minimum numbers of the main prey types were: rabbit 141, bird 122 and reptile 52. Prey remains were collected at the same time as the pellets and on comparison, there were similar counts of rabbits (134) in the prey remains as in the pellets, more birds (159) and fewer reptiles (34). 

The pellets were collected from below roosting branches. The larger one shown here was more likely from a female eagle and the other two from a male. This is because the female birds are much larger than the males and are more likely to eject larger pellets, although this is not conclusive as there is considerable overlap in the pellet sizes, as that can be affected by the prey eaten and size of the meal.

The main contents of this pellet can be seen. It is mostly composed of rabbit fur and whiskers, and there are feathers, probably from either a Crimson or Eastern Rosella.

This pellet is also mostly composed of rabbit fur. The secondary item is a lizard as can be seen by the scales and claws in the lower end. Possibly a Cunningham's Skink.

A total of 810 pellets were collected over three years. Each pellet was individually bagged and labelled. And all pellets that were collected at the same place and time were bagged into batches. Then all pellets from each year were bagged together. They were all dried thoroughly prior to bagging to preserve the contents. Then they were all analysed one after the other. It is easier to do this all at once as familiarity of the various items speeds identification.

There is a lot more to fieldwork than fieldwork.

The fourth annual report on the study of Little Eagle breeding in the ACT area - 2020

A fledgling Little Eagle perches on a branch at the edge of its nest while the adult female looks on from a branch behind the nest.

BREEDING SUCCESS AND DIET OF LITTLE EAGLES IN THE ACT AND NEARBY NSW IN 2020

Rae, S., Mulvaney, M., Wimpenny, C., Brawata, R., Stol, J., Davies, M., Roberts, D. and Olsen P. (2021). Breeding success and diet of Little Eagles in the ACT and nearby NSW in 2020. Canberra Bird Notes 46: 56-73. 

Abstract. Twelve Little Eagle (Hieraaetus morphnoides) territories were occupied in the ACT in 2020. There were nine pairs, seven of which were confirmed to have nests, and it is not known if the other pairs had nests. There were single birds, a male and female, at two territories, and at one previously successful territory a female was seen with a lined nest but no male and no eggs were seen. Eggs were laid in at least six nests and young were hatched in all nests with eggs laid. At least three chicks died while still young, two in each of two nests with single chicks. Prolonged heavy rainfall was a possible cause of failure at these two nests and one nest was disturbed by Pied Currawongs (Strepera graculina) and Brown Goshawks (Accipiter fasciatus) probably causing chick death. A minimum of three pairs successfully fledged one chick each. In nearby NSW, four previously known nest sites in NSW were occupied and single young fledged from all. One chick died in one of these nests where two chicks had hatched. A fifth, new, pair with a nest were located but they apparently did not lay eggs. Despite higher loss of nestlings than in the previous three (drought) years, overall breeding success was slightly higher. The diet was composed of mammals (60.6%), of which European Rabbit (Oryctolagus cuniculus) was 52.4%, small/medium-sized birds (36.1%) and reptiles (3.3%). Rabbits made up a greater percentage of the diet than in the previous three breeding seasons.

Another fledgling Little Eagle, a dark phase one, flies over its nest area.

After three dry years, the wet winter and spring in 2020 began promising for the Little Eagles breeding in the ACT. The vegetation grew back after the rains and rabbits, a major food source for the eagles, were abundant. A higher proportion of eagle pairs laid eggs and hatched young than in the previous three years. However, the wet weather continued with some prolonged heavy rainfall when the chicks were still downy and vulnerable to hypothermia. This could have been the main cause of failure this year, or perhaps the adults could not find enough food during the rain periods and the chicks starved. What happened is uncertain, and it is only when we study birds closely that we detect such occurrences. One reason why this is a long-term study, is to collect data from enough years to assess how such factors as annual variations in weather can affect the birds breeding success.