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Identification and Aging

Linda M. Tuttle-Adams

Introduction

Identifying the species and assessing the age of chicks, especially those that arrive mostly naked or
with a few downy feathers, can seem daunting (Figure 2.1). However, there are many reasons to
make the effort as soon as possible, because species and age play an essential role in such decisions
as reuniting versus fostering, diet, housing, and psychological development needs. This chapter
describes the primary characteristics that help identify a chick’s species (or at least place it in a
family group) and help assess its age.
Although many of the basic needs of baby birds are similar, each species has unique require-
ments based on its physiological and psychological makeup. For example, except for some baby
finches that need regurgitated seeds, nearly all passerine nestlings are fed arthropods (mainly
insects). Misidentification can result in a baby bird being fed the wrong diet, which may have con-
sequences for its health.
The difficulty with chick identification begins with a lack of readily available and compre -
hensive guides like those covering adults. Creating a guide to cover just the 900+ North
American breeding species would be an insurmountable task, as it would need to include all
the stages of development and subspecies variations. Additionally, there are many gaps in the
knowledge about some species because of their secrecy in breeding behavior and inaccessibility
of nests (Rodewald 2015). Relying on photos alone to identify a chick comes with its own set of
issues, such as color interpretation and, of course, the inability of photos to convey behaviors
and vocalizations. Moreover, photos often lack such information as size, weight, and location.
One needs to know what key features to look for before searching through references, so it’s
essential to study the bird itself and recognize key features in order to reduce errors and arrive
at a correct identification.
Social development is a very important aspect to address when captive‐rearing birds. A nec-
essary form of learning where a chick learns to recognize others of its own species is called
imprinting. Imprinting occurs during a time in a young bird’s life called the “sensitive period,”
beginning with the onset of focused vision (Bateson 1966, 1979; Welty and Baptista 1988). In
precocial birds that hatch with their eyes open, imprinting on a parent (called filial imprint -
ing) is immediate. In altricial birds, filial imprinting occurs around the second week of life, or
later depending on species, when the eyes are fully open. After this initial period, birds may go
through a period called sexual imprinting, when they learn mate preferences. During the

Hand-Rearing Birds, Second Edition. Edited by Rebecca S. Duerr and Laurie J. Gage.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.