Abstract
Avian postnatal growth has received considerable attention and its ecological implications have been deeply analyzed. In this current paper, I describe the patterns of culmen and tarsus growth, as well as of weight gain patterns in eight species of herons and egrets (Aves: Ardeidae) found in the Birama Swamp in Eastern Cuba. Between 1998 and 2006,714 nestlings of the following species were measured every two days: Butorides virescens, Bubulcus ibis, Egretta thula, E. tricolor, E. caerulea, E. rufescens, Ardea alba and Nycticorax nycticorax. Logistic and Gompertz equations were adjusted to data using non-lineal regression models with adult values as the asymptote. For each species, the following were determined and recorded: growth rate, age at inflexion, instantaneous growth rates at each age interval, and time taken to reach 90% of adult size. Reported hatchling sizes were similar in other localities, with a variation coefficient ranging between 10-19%. At hatch, each species exhibited differing sizes relative to adult values. In all cases, Gompertz equations were best fitted to explain more variance and lesser residuals. Rates of weight change and tarsus growth were alometrically related to the log of adult weight. Two main growth processes were identified: a physical extension in dimensions of each measurement reflecting inter-specific morphometric differences, and a lineal increase of the growth period from Green Heron to Great Egret. The Black-crowned Night Heron, Cattle Egret and Reddish Egret exhibited some unique measurement characteristics in comparison to the remaining members of the family. All results support the hypothesis that hypermorphosis, as the main evolutionary process in the microevolution of Ardeidae, is caused by a delayed final moment of growth.
Highlights
Las dinámicas representadas en la forma y velocidad de las curvas de crecimiento de las diferentes estructuras corporales en las aves han sido moldeadas durante la evolución bajo numerosas presiones selectivas (Gill 1998)
The seasonal decline in Tree Swallow clutch size: physiological constraint or strategic adjustment? Ecology 77: 922-932
Summary
El trabajo se realizó en la ciénaga de Birama, provincia Granma, en el área comprendida dentro del Refugio de Fauna “Delta del Cauto” (20°28’ N - 77°10’ W) en el período comprendido entre los años 1998 y 2006. Si bien el crecimiento en las dos primeras semanas tiene un comportamiento cercano a una recta, no es adecuado aplicar un modelo de regresión lineal al no cumplirse los supuestos de estos métodos, en particular la independencia de los valores y la homogeneidad de varianza, además de que este método ignoraría las diferencias en valores finales teóricos del crecimiento en cada especie, que pueden influir notablemente en los estimados de constantes de crecimiento. El ajuste no lineal se realizó por el método de Levenberg- Marquardt (combinado con el método de movimiento de patrones de HookeJeeves), y como medida del ajuste se tomó el porcentaje de varianza explicada por el modelo y la desviación estándar de los residuos, para seleccionar el modelo que más se acerca a los datos. CUADRO 1 Medidas de los adultos de ocho especies de garzas (Aves: Ardeidae) empleadas como asíntotas en el análisis del crecimiento
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
