Blue-throated bee-eater

Blue-throated bee-eaters make a combination of vocalizations characterized as longcalls, alarm calls, chirps, low chirps, purrs, sharp coos, trills, and feeding calls.[4] Longcalls have been observed to communicate long distances and are recognizable by their volume and intensity.[4] A longcall is performed either during flight or on a perch by stretching and pointing their bill upwards, known as a “longcall” posture.[4] Chirps are short and sharp with regular intervals, often used during digs.[4]

Courtship offering of an insect from male to female

Blue-throated bee-eaters have a generation rate of around 6.2 years.[5] They practice asynchronous brooding, meaning parents begin brooding at different times.[6] This results in hatching of chicks at different times. The eggs hatch over a period of ten days with an average spread of 4.43 ±12.15 days.[6] The sequence and timing of the hatching of chicks is correlated with size, with the first-born chick having the greatest mass.[6] Parents lay two to seven eggs with a survival of zero to three chicks raised to fledging.[6] The chicks normally die in order, starting from youngest and smallest.[6] The observed death rate in chicks was largely caused by sibling attacks by utilizing a sharp hook on the upper bill, later lost in development, and inflicting wounds on the naked head of other chicks.[6] Those chicks who are older have time to grow more contour feathers, protecting them from damaging attacks.[6] Siblicide is common among other birds to increase the larger and older chick's survival with greater access to food by the parents.[6] Sibling attacks are more common among birds when food is scarce and monopolized.[7] In the blue-throated bee-eater's case, insects are delivered one by one to the chicks, making food easily monopolized to chicks with the greater advantage.[6] Increasing brood size did not increase the survival of the chicks.[6] Decreasing body mass is correlated with increasing wounds and scars found on the individual chicks, which increased the likelihood of death.[6]

They predominantly feed on flying insects such as bees and wasps.[2] Other insects caught include flies, beetles, and other bugs up to 42mm.[3] A large percentage of the blue-throated bee eater's diet consists of dragonflies with highest success rate of their catches in sunny conditions.[4] Observations found no feeding activities during rain and right after showers.[4] Their feeding patterns are well-matched with the seasonal weather patterns.[4] The highest feeding rate is during breeding season, perfectly matching the sunniest period, right after the rainy season.[4]

Each spring, blue-throated bee-eaters (Merops viridis) along with blue-tailed bee-eaters (Merops philippinus) migrate from Sumatra, cross the Straits of Malacca, and end up on the west coast of Malaysia.[8] The observed flight locomotion from Tanjung Tuan, west coast of Malaysia, was a combination of flapping and gliding flight.[8] Occasionally, they would use the air currents from the sea-breeze to soar upwards.[8] Once reaching land, they would rest on the lighthouse and tree branches for up to ten minutes before continuing eastward.[8] This migration was observed from 2000 to 2001 with a total of 2,226 bee-eaters, with 1353 blue-tailed bee-eaters, 222 blue-throated bee-eaters, and the rest unidentified.[8] The most observed migrating bee-eaters occurred on 21 March 2000 between 1-2PM.[8] The high number observations of bee-eaters were most likely due to the strong thermals that formed over Sumatra, allowing them to soar over the sea-breeze with ease.[8] High numbers of bee-eaters were also observed to migrate when there were high westerly winds blowing towards Malaysia.[8] Blue-throated bee-eaters also migrate onto breeding grounds of western China during breeding season as shown in the range map above. [9]