Growth of little stint Calidris minuta chicks on the Taimyr peninsula, Siberia

Growth of mass and linear body dimensions (bill, tarsus and wing length) was studied in the Little Stint Calidris minuta at several locations on the Taimyr Peninsula, Siberia (73 degrees-76 degrees N) in 1983-94. Little Stints fledged at near-adult body mass, at 15 days of age. Growth followed an S-shaped pattern which was best described mathematically by a logistic curve. Curves of this type showed that growth was similar between study sites and years, although there were differences in mass development during the first days after hatching, perhaps related to weather conditions. When the logistic growth curve was used, K-L (the standard measure of maximum growth rate) was 0.285. Conversion of this parameter to another S-shaped curve, the Gompertz curve which has been widely used to describe wader chick growth, yields K-G = 0.194. This is higher than predicted from an allometric relationship based on 15 other precocial wader species, and might be related to the Little Stint's high latitude breeding range

Growth of Little Stint Calidris minuta chicks on the Taimyr Peninsula, Siberia

Growth of mass and linear body dimensions (bill, tarsus and wing length) was studied in the Little Stint Calidris minuta at several locations on the Taimyr Peninsula, Siberia (73 degrees-76 degrees N) in 1983-94. Little Stints fledged at near-adult body mass, at 15 days of age. Growth followed an S-shaped pattern which was best described mathematically by a logistic curve. Curves of this type showed that growth was similar between study sites and years, although there were differences in mass development during the first days after hatching, perhaps related to weather conditions. When the logistic growth curve was used, K-L (the standard measure of maximum growth rate) was 0.285. Conversion of this parameter to another S-shaped curve, the Gompertz curve which has been widely used to describe wader chick growth, yields K-G = 0.194. This is higher than predicted from an allometric relationship based on 15 other precocial wader species, and might be related to the Little Stint's high latitude breeding range

Body mass patterns of little stints at different latitudes during incubation and chick-rearing

Due to the 'double-clutch' mating system found in the arctic-breeding Little Stint Calidris minuta, each parent cafes for a clutch and brood alone. The resulting constraint on feeding time, combined with the cold climate and a small body size, may cause energetic bottlenecks. Based on the notion that mass stores in birds serve as an 'insurance' for transient periods of negative energy balance, but entail certain costs as well, body mass may vary in relation to climatic conditions and stage of the breeding cycle. We studied body mass in Little Stints in relation to breeding stage and geographical location, during 17 expeditions to 12 sites in the Eurasian Arctic, ranging from north Norway to north-east Taimyr. Body mass was higher during incubation than during chick-rearing. Structural size, as estimated by wing length, increased with latitude. This was probably caused by relatively more females (the larger sex) incubating further north, possibly after leaving a first clutch to be incubated by a male further south. Before and after correction for structural size, body mass was strongly related to latitude during both incubation and chick-rearing. In analogy to a similar geographical pattern in overwintering shorebirds, we interpret the large energy stores of breeding Little Stints as an insurance against periods of cold weather which are a regular feature of arctic summers. Climate data showed that the risk of encountering cold spells lasting several days increases with latitude over the species' breeding range, and is larger in June than in July. Maintaining these stores is therefore less necessary at southern sites and during the chick-rearing period than in the incubation period. When guarding chicks, feeding time is less constrained than during incubation, temperatures tend to be higher than in the incubation period, reducing energy expenditure, and the availability of insect prey reaches a seasonal maximum. However, the alternative interpretation that the chick-tending period is more energetically stressful than the incubation period, resulting in a negative energy balance for the parent, could not be rejected on the present evidence