The smallest diurnal predator in Africa has been studied for the first time using GPS trackers. The results showed that to feed its chicks, this bird requires a territory almost 14 times smaller than that of its closest competitor—the lesser kestrel.

Features of the African Pygmy Falcon

The African pygmy falcon (Polihierax semitorquatus) weighs about 57 grams and is considered the smallest bird of prey on the African continent. In the southern part of its range, this species is often found near sociable weavers—small songbirds that build large communal nests. The falcons use these nests for roosting, breeding, and hunting weavers and other colony inhabitants.

Use of GPS Trackers

Studying the movements of small birds is challenging because tracking devices must be extremely lightweight, not exceeding 3% of the bird’s body weight to avoid interfering with flight. For the first time, GPS trackers were used to observe the behavior of these predators. In a study conducted in the Tswalu Kalahari Reserve in South Africa, trackers were attached to 18 adult birds. The devices, including their harnesses, weighed 2.2–2.4 grams, which is about 4% of the bird’s weight. The trackers transmitted coordinates every 30 minutes and remained on the birds for no more than 15 days due to weight and technical limitations.

Observation Results

Data were obtained from 13 individuals: three trackers were lost, and one device was removed from a bird due to flight difficulties. On average, 295 location points were collected per bird. The average hunting territory size was 0.93 square kilometers, nearly 14 times smaller than that of the lesser kestrel, previously considered the record-holder among GPS-tracked birds of prey. The pygmy falcon’s territory is also about 27 times smaller than that of its larger African relative, the black-shouldered kite. Thus, the smaller the bird, the smaller the territory it needs.

Comparison of Male and Female Territories

The hunting territories of males and females were almost identical: males averaged 0.98 km², females 0.87 km². This indicates that both parents equally participate in feeding the chicks, unlike many other birds of prey where the male hunts and the female stays at the nest. Sometimes pygmy falcons nest in groups, but due to the small sample size, the impact of this factor could not be assessed.

Impact of Trackers and Research Prospects

The trackers did not interfere with the birds’ normal activities: all individuals, including the one from which the device was removed, continued to feed their chicks after the trackers were attached and removed. Of the eight territories observed, chicks appeared in six.

The collected data only cover the chick-rearing period. In other periods, such as after the chicks leave the nest, the territory size may increase. To fully understand the lifestyle of this species, observations are needed in different seasons and outside the breeding period.