Ephemeral streams are small headwater streams that only experience streamflow in response to a precipitation event. Due to their highly complex and dynamic spatial and temporal nature, ephemeral streams have been difficult to monitor and are in general poorly understood. This research implemented an extensive network of electrical resistance sensors to monitor three ephemeral streams within the same small headwater catchment in Southern Ontario, Canada. The results suggest that the most common patterns of network expansion and contraction in the studied streams are incomplete coalescence and disintegration, respectively. Binary logistic regression analysis of the primary controls on ephemeral streamflow showed only weak Nagelkerke R2 values, suggesting that there are more complex processes at work in these ephemeral streams. A comparison of all three streams suggests that even ephemeral streams within the same subwatershed may experience differences in network expansion and contraction and may be dominated by different spatial and temporal controls. Copyright © 2013 John Wiley & Sons, Ltd.