Blue-naped mousebird

Solitary birds perched atop trees emit a distinct and resonant "tieee" whistle every 3–5 seconds. While foraging, it produces a shorter and less robust version of the same call, spaced at longer intervals of 10–15 seconds. In groups, a pre-flight ritual includes a collective "trie-trie" before departing the feeding area, or a rhythmic "tsie-tsie..." every 0.5 seconds just prior to takeoff. In flight, the sound transforms into variations like "trui-tru-tri," "triu-triu," or "tri-truu-truu...". A begging female vocalizes a unique sequence, described as "cruir-uu-tuit-truit," during courtship while the male utters a series of "tiuee-tuiee..." notes at a rate of six every approximately 10 seconds. Perched birds contribute to the auditory landscape with occasional weak trills and individual notes.[3][5]

The birds are mostly sedentary, with occasional local nomadic behavior. Particularly in Senegal, Mali, Kenya, and Tanzania, routine dry-season movements occur, where they transition from savanna woodland to river valleys and populated areas[4]. Infrequent sightings of the species in Benin [15], Gambia, and Guinea-Bissau are likely the outcomes of these movements.

Primarily, these birds rely on fruits as their main food source, and they also eat leaves, flowers, and buds[9][4]. Bird have been seen foraging for food together, one of the few common arboreal bird species to do so[4] In some regions like Niger and Chad, the berries of the Salvadora persica plant are especially crucial. Other plants they utilize include Balaenites aegyptiaca, Capparis decidua, Boscia senegalensis, Grewia villosa, Tamarindus, and Ficus. Additionally, they consume dates and various cultivated fruits, with a preference for those from the Azadirachta indica tree, commonly found in towns [3].

These birds are often seen in groups of up to ten individuals, but sometimes as many as 50 may gather around a single fruiting tree. They move in flocks, traveling from one known fruiting tree to another, stopping to forage every 20–200 meters (usually around 85 meters). They follow the same route at the same time each day [3].

Nest of blue-naped mousebird

Breeding occurs throughout the year and peak season varies  based on the region and is typically during or just after the rainy seasons: May-Jun in Nigeria, May-Jun and Dec- Feb in Northern Sudan, Apr-Jul in Ethiopia, May in Kenya, and Mar-Jun in Zaire[5]. They have been observed to display monogamous tendencies in captivity where pair-bonds endure for extended periods, and are likely territorial in nature, but perhaps a co-operative breeder[3]. The nest is a shallow and disorderly cup made of twigs, sparsely lined with grass and rootlets[3][5]. Material is brought by the male and assembled by the female. It is typically positioned in a tree or thorny bush, approximately 3–4.5 meters above the ground. The usual clutch consists of 2–3 eggs (though occasionally 1–4), with whitish shells adorned with rufous or brown markings, measuring around 20.3 mm × 14.5 mm[3][5]. Incubation begins with the first egg and is a joint effort by both sexes, with the female taking over during the night and the male during the day[3][5].

The incubation stage observed in captivity spans 11 days [3]. The chick once hatched, weighs around 2.3 grams[13], and exhibits distinctive bulbous swellings at the base and on both sides of the lower mandible, which persist for approximately one month and before it disappears[3]. The chicks may venture out of the nest around 10–12 days when they have attained 55% of adult mass [13]. Their inaugural flight occurs around 16–17 days, but they still return to the nest until they are 21 days of old[3]. They are dependent on adults for sustenance for about six more weeks before they only attain adult body mass around 15 weeks of age [3][13]. Longevity in capativity has been up to 11 year and five months.