ee RON ane 4 + Seed TRAV IP SGA OSI OE | Bre ¥>) y Spoiee adds wich: vide Tot pi bs. eee ‘ ' der 7 roe erent fe , ot pao et htt et hire f ' ap he Pent: A OS ass ? : age She 7 oa A r “ ‘ YY ne" ° Px j as are even veel . oe SO me oo On NeeSeolenlt q ; ~. . : ea 5 3 x Leciee y O A sees nea ape eee ; mde 5 Fare mest sacha: a ARS ae Pes caodew wild pha 2 YVORO) ‘ane 6%. ow haan as. orn has matin a £98 § tae Po A Pie nG tad d ie Bee Seton ORIG AL EE os og! er te aes Sie eee 5 STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION NATURAL HISTORY SURVEY DIVISION A GUIDE TO AGE DETERMINATION OF BOBWHITE QUAIL EMBRYOS RLS Up ns WA) John L. Roseberry Willard D. Klimstra Illinois Natural History Survey Biological Notes No. 55 Urbana, Illinois July, 1965 IDENTIFICATION of the various incubation stages of eggs is often necessary in avian nesting studies. This paper provides a descriptive and illustrative guide to age deter- mination of bobwhite quail (Colinus virginianus) embryos. It supplements the work of Hanson (1954), who deter- mined embryonic development by candling eggs, and of Essex (1952), whose descriptions and drawings of bob- white embryos appeared in an unpublished thesis. This paper is published by authority of the State of Illinois, IRS 127, Par. 58.12. It is a contribution from Project No. 1 Bobwhite Quail Life History and Population Studies, Southern Illinois University and the Illinois Natural History Survey cooperating. John L. Roseberry is Assistant to the Director of the Cooperé Wildlife Research Laboratory Southern Illinois Univer Carbondale Dr Willard D. Klimstra is Professor of gy and Director of the Cooperative Wildlife Research Laboratory, Southern Illinois University and Con- sultant in Wildlife Research, Illinois Natural History Survey. Fig. 1 and 2 represent the chronological sequence of development of the bobwhite embryo. The brief descrip- tions of each daily stage are based on prominent external characteristics visible to the unaided eye. Eggs were obtained from the Mount Vernon Game Farm, operated by the Illinois Department of Conserva- tion, and incubated in a Farm Master incubator under standard incubating conditions (temperature 99.5° F., hu- midity 55%-60% ). At least four eggs were examined at approximately the same hour each day of the incubation period. The embryo most representative of the mean de- gree of development each day was photographed and de- scribed. The embryo photographs were taken by Robert Hanzlik, a senior at Southern Illinois University. The nest photograph was taken by the senior author. FIG. 1.—Stages of development of bobwhite embryos 0 u FIG, 2.—Stages of development of bobwhite embryos 15 through 23 days old. We 8) 10 Descriptions of Embryonic Development Day (unincubated): Slightly cloudy area present on surface of yolk; blastoderm appearing as white opaque spot 2 mm in diameter in center of this cloudy area. Day: Blastoderm resembling a bull’s-eye about 10 mm in diameter with a small dark central spot surrounded alternately by lighter, darker, and lighter circular areas. Embryo proper and blood vessels not yet visible. Days: Tiny blood vessels forming an irregular oval 8-10 mm in diameter, with unflexed embryo lying in clear area in the center; heartbeat not yet visible. Days: Embryo, 5-6 mm long, lying transversely to longitudinal axis of egg; slightly arched and rotated to the right anteriorly. Heartbeat visible. Days: C-shaped embryo lying on its left side; eye visible as dark pigmented spot 1 mm in diameter. Anterior limb buds discernible as small bumps. Choroid fissure and heartbeat evident. Days: Embryo C-shaped and with prominent eye. Choroid fissure, cerebral hemispheres, and midbrain obvious; auditory openings barely visible. Limb buds appearing as flaplike structures 1 mm long. Allan- tois appearing as transparent structure, 34 mm in diameter, below lower limb bud. Days: Eye about 2 mm in diameter; choroid fissure and auditory openings clearly visible. Cerebral hemi- spheres and midbrain conspicuous. Anterior limbs slightly flexed at elbow joint, posterior limbs covered by allantois, which appears as a spherical sac 5-6 mm in diameter. Days: Embryo still C-shaped, with head nearly as large as body. Cerebral hemispheres and bilobed midbrain still conspicuous. Eyelids and upper mandi- ble beginning to form. Forelimbs terminating in a broadened paddle. Long bones of anterior and pos- terior limbs visible as opaque white bars. Allantois covering entire embryo; heartbeat evident. Days: Body and head nearly equal in size. Choroid fissure barely visible; iris visible and eyelids well formed. Knee and elbow joints flexed. Cerebral hem- ispheres less pronounced, but midbrain still promi- nent; upper mandible projecting from face. Heart- beat still visible. Days: Center of each eye encircled by ring of white dots, nictitating membrane present. Cerebral hemis- pheres and midbrain much reduced; lower mandible well defined. First digit of each foot visible and wing alulae appearing as thumblike projections. Feather germs visible as band of white dots along center of back. Heartbeat barely discernible. Days: Eyelids beginning to close over eyes. separated from manus and patagia formed. Digita- tion of feet well advanced. Dark feather papillae on back; feather tracts of head appearing as light dots. Mandibles assuming normal beak shape; egg tooth visible. Heartbeat no longer evident. Days: Head more rounded but still large in propor- tion to body; choroid fissure no longer visible. Digi- tation of feet now complete; toes showing deposition of keratin at tips. Dark down feathers appearing on back, thigh, and tail. Cloacal opening visible. Alulae CLOS10 5M 14 15 16 17 18 ESSEX, J. HANSON, HAROLD C. Days: Feathers on back, thigh, tail, and scapular region darkly pigmented; those on back and thigh showing color differentiation. Feather germs on eyelids white. Keratinization of claws continuing; plantar pads be- ginning to form on feet. Days: Dark feathers prominent on back, thigh, tail, and posterior edge of each wing. Feather germs encircling auditory openings dark. Scales beginning to form on legs and feet. Nostrils evident and eye- lids closing to narrow slits. Days: Feathering greatly advanced over that of previ- ous stage; dark feathers around auditory opening appearing in the form of a semicircle. Inside edges of eyelids darkly pigmented. Dark band of feathers extending between auditory opening and eye. Days: Eyelids virtually closed. Dark feathering around auditory opening a complete circle; feathers on breast long but colorless. Uropygeal gland showing feathered tab above opening. Serrated edge (labial grooves) apparent on lower mandible. Days: Feathering on head greatly advanced over that of previous stage; breast feathers showing dark spots at base. Feathers brown on upper eyelids, white on lower. Cornified epidermis formed at tips of wing alulae. Days: Embryo almost entirely covered by down feath- ers; uropygeal gland well hidden. Yolk intensely yellow in color. Eyelash structures apparent. Toenails well developed. Days: Size of eyes appearing normal in relation to head. Yolk, wrapped around feet and legs of em- bryo, with a dark greenish tint. Yolk stalk and audi- tory openings plainly visible. Days: Scaling of legs nearly complete. Auditory openings well hidden by feathers. Yolk being drawn into body; stalk no longer visible. Position of embryo as follows: lying on left side, with eye, ear, and bill visible; right leg bent so that foot is touching top of head; right wing in normal position at side. Epi- dermal tip on wing alula partly hidden by feathers. Days: Embryo in following position: head rotated to right, and right wing shifted over head. Elbow joint still bare of feathers; periderm still covering egg tooth. Days: Peridermal covering lost from beak. Back arched into pipping position, head covered by right wing; air cell punctured by bill, which is projecting from under right wing; pipping tooth nearly touch- ing shell. Yolk concentrated around feet; embryo breathing when removed from egg. Days: Upper mandible brownish. Yolk sac reduced to sphere 1 mm in diameter. Embyro able to open eyes when shell is removed; pipping commencing. Days: Pipping completed; embryo emerging as hatched quail chick. LITERATURE CITED R. 1952. Aging techniques applicable to bobwhite quail embryos and juveniles. Masters thesis, Ohio State Uni- versity, Columbus. 72 p. 1954. lard, wood duck, and bob-white quail eggs. 267-272. 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