Early Hatch and Managed Native Grasslands Minorly Improve Bobwhite Juvenile Body Condition

Abstract

Precocial young leave their nest immediately after hatch to move and forage as a group during a rapid period of development. Growth and body condition are correlated with survival; young are better able to thermoregulate as they become larger, and they are better able to escape predators as they become more mobile. Environmental conditions can influence development and ultimately survival. We evaluated weather, cover type, and temporal factors affecting northern bobwhite juvenile body condition. We captured 216 individuals from 33 broods >16 d old on five conservation areas in southwest Missouri in 2017 and 2018. Brood hatch dates ranged from 26 May through 19 September. Body condition was measured as the residuals from a linear regression of juvenile tarsus length and body mass on capture. We found some support for improved body condition earlier in the breeding season and in native grasslands that were burned and grazed within the previous 2 y. However, models representing these effects had similar support to the null model (i.e., ΔWAIC<2), indicating weak support. Limited support for these effects may have been due to limited data or the influence of other environmental factors not considered in our competing model set. Our top model supported negative effects of later hatching date and agricultural crop cover on juvenile body condition. The early breeding season is an important period for successful bobwhite productivity, and native grasslands managed with rotational fire and grazing may create higher quality brood rearing habitat for improved juvenile body condition.