Mousebirds are extremely social and gregarious, spending their life in specific flocks, and solitary mousebirds in the wild are rare. Socializing to this degree offers health advantages as well as some protection from predators. Mousebirds forage for food, groom, bathe, and play together, as well as nest and raise young communally. They are territorial, and together will defend nest sites and food sources. Adults, and especially young birds, spend time with each other in complex play activities and play with objects in their environment, such as twigs and leaves.
They have a hierarchical structure in which there is usually a dominant male and female. As in most societies, peace does not reign continuously. Squabbles, chases, and fights often break out, and usually the loser is allowed to escape. Birds, particularly young adults upon maturity, do leave one flock to join another, and strange mousebirds are viewed with suspicion before being accepted into a new flock.
Being very tactile creatures, mousebirds crave contact with others, following each other around and roosting next to one another. Allopreening and allofeeding behaviors, in which birds groom and feed each other, are common. They communicate well vocally with a variety of calls and whistles used for different purposes including alarm and greeting calls.
As will be discussed in the following chapters, mousebirds are so gregarious, they are not happy unless they have daily contact with another in their “flock”, be it another mousebird, another type of bird, or a human. Keeping a mousebird isolated from such contact would be cruel and heartless.
Mousebirds are often seen hanging from branches in clusters of two or more birds. They huddle against one another at night and at various times during the day, particularly in cold weather. They sleep hanging belly to belly, or several cluster into one ball. Clusters containing twenty-eight birds have been documented! They mesh so tightly that it is hard to see just how many birds are in a pile-up sometimes. Rarely will a mousebird sleep alone if others are around.
Picture 1: Group of six White-headed Mousebirds clustering, belly to belly, at night.
In a daily morning ritual, they seem to literally worship the sun’s rays. Fluffing their feathers, spreading their wings, standing as erect as possible and stretching back with eyes closed in ecstasy, they are overcome with pleasure, sometimes to the point of losing their balance. Looking like a puffball, they turn themselves, belly foremost, as if on a cooking spit, to expose all parts of their bodies, preening joyfully. Sunning and clustering are activities not just for their mental well being, their health is directly tied to the sun and each other. One of the most interesting things about mousebirds is their thermal physiology.
Picture 2: Handraised White-backed Mousebird sunning. Notice the open wings, tilted back posture, and fluffed feathers.
Clustering, sunning, torpor, and sociability are all evolutionary tactics that are interconnected to help ensure the mousebird’s survival in an environment with food that is relatively low in energy and often unpredictable in availability. To reduce energy output, especially in harsh conditions, mousebirds huddle together to share body heat. Their body’s metabolism can be dramatically lowered, sometimes by 90%, and the mousebird enters a torpid state similar to hummingbirds’, where they appear to be in a deep sleep, and their bodies are actually cold to touch. In the morning, they warm up quickly by sunning themselves.
Using the solar radiation appears to be a significant energy saver as are the clustering and torpor techniques. Aiding digestion of fibrous plant material may also be a benefit of sunbathing. With the evolutionary advantage of being able to absorb solar heat quickly comes the trade-off that mousebirds have a hard time regulating and controlling their own body temperatures. This furthers the bond the mousebirds have to one another; they must be sociable to survive. The harsher the environment, the more sociable they are, but even on warm days they will still cluster, reaffirming the social ties.
Several interesting studies have been and are currently being done on this aspect of mousebird’ physiology and surely more will be known in the future.
The mousebird’s physiology is unique and must be taken into consideration when planning housing for mousebirds. Having a single bird requires more planning then a pair or group of birds. Cold temperatures can easily kill a single bird while a group of birds will be able to handle the cold better. Cold is the number one killer of mousebirds in captivity. Supplemental heating is ideal for groups of birds and a must for single birds kept outside in all but the mildest climates.
A bird that has not fed before nightfall will be stressed and may enter a torpid state. Feeding mousebirds in the morning and again an hour or so before nightfall is recommended especially if housing a single bird that is alone, young, or new to the enclosure. Birds that are unhealthy or stressed by other factors will often enter a state of deep torpidity and may not be able to be revived. Young birds become torpid much more easily than adult birds, even at household temperatures.
Torpid mousebirds are lethargic, cold, and usually clamped into their sleeping position. They can be mistaken for sick birds, but if the bird does not become normally active after being in the sun or warmed up, or enters torpid states at mild temperatures, it may be unhealthy. Any mousebirds that are found “dead” in the morning should be carefully examined and warmed up just in case the bird is actually in a torpid state and surprises the owner by reviving.