One of the most significant challenges in implementing ecological restoration is developing scientifically justifiable targets and assessing progress towards those targets. The Comprehensive Everglades Restoration Plan (CERP) identified as a major goal the reversal of marked decreases in wading bird nesting success in the Everglades. To assess progress towards this goal, a hypothesis was developed stating that a key cause of the wading birds’ decline is the decrease in concentrations of small fish and crustaceans that provide food during the nesting season. Furthermore, it is hypothesized that recovering historical hydrological patterns will restore concentrated prey in locations and at times they are needed to support wading bird nesting. We chose a set of small fish and crustaceans with different responses to hydrology as indicators to track progress towards restoration goals. We modeled the responses of these indicators to hydrological parameters using historical data, and modeled predictions of the same hydrological parameters based on stated restoration targets. This yielded dynamic quantitative targets for the prey density indicators that we can compare to densities measured in monitoring sites throughout the Everglades. We then used a report card system to provide an easily digestible assessment of how well these targets are being met.
Results/Conclusions
We have used this model-based system since 2006 to provide biennial assessments of the CERP. Measured densities of bird prey indicators have generally been below our modeled targets, and with some exceptions fail to demonstrate positive trends. However, there is substantial spatial heterogeneity: 53% of monitoring sites met targets this year, while two of the four major study regions are consistently not meeting targets and some sites show declines. Since our models account for rainfall patterns, failure to reach sufficient prey densities may be attributed to water management practices that should be improved. For example, the dry season in Taylor Slough in the southern Everglades has been prolonged by timed water release by managers, which has had a negative effect on bird prey densities. Completion of new hydrological features designed to improve water delivery and retention is anticipated to reverse this trend. Our report card assessment thus gives managers specific information as to where and how densities of these animals can be increased in order to begin to meet restoration targets.