Health Status of Great Frigatebirds (Fregata minor) Determined by Haematology, Biochemistry, Blood Gases, and Physical Examination

Abstract

The great frigatebird, Fregata minor, is a widely distributed seabird native to the Galápagos archipelago. Haematology and blood chemistry parameters have been published for this species but not from the San Cristóbal and North Seymour great frigatebird breeding colonies. Analyses were run on blood samples drawn from 25 great frigatebirds captured by hand at their nests at Punta Pitt on San Cristóbal Island and 30 birds on North Seymour Island, Galápagos Islands. A portable blood analyser (iSTAT) was used to obtain near immediate field results for pH, pO₂, pCO₂, TCO₂, HCO_3^- , haematocrit (Hct), haemoglobin (Hb), sodium (Na), potassium (K), chloride (Cl), ionized calcium (iCa), creatinine, urea nitrogen, anion gap and glucose. Blood lactate was measured using a portable Lactate Plus™ analyser. Average heart rate, respiratory rate, body weight, body temperature, biochemistry and haematology parameters were comparable to healthy individuals of other Fregatidae. The reported results provide baseline data that can be used for comparisons among populations and in detecting changes in health status among Galápagos great frigatebirds.

Keywords: Biochemistry; Fregata minor; Galápagos Islands; San Cristóbal; blood gases; haematology; health status.

Figure 1:

This high magnification photomicrograph illustrates three different white blood cells (A = eosinophil; B = thrombocyte; C = lymphocyte) amongst numerous red blood cells. Eosinophils have muddy pink granules and a lobed nucleus, whereas lymphocytes have a distinctive round nucleus with clumped chromatin and clear blue cytoplasm. Diff Quik stain, 1000×.

Figure 2:

This high magnification photomicrograph illustrates two different white blood cells (A = heterophil; B = lymphocyte) amongst numerous red blood cells. Heterophils showed pink round granules and big vacuoles, whereas lymphocytes have a distinctive round nucleus with clumped chromatin and clear blue cytoplasm. The heterophil and lymphocyte are surrounded by erythrocytes. Diff Quik stain, 1000×.

Figure 3:

This high magnification photomicrograph illustrates a Haemoproteus sp. gametocyte inside a red blood cell. Diff Quik stain, 1000×.