MODELLING THE EFFECTS OF RIVER FLOW ON POPULATION DYNAMICS OF PIPING PLOVERS (CHARADRIUS MELODUS) AND LEAST TERNS (STERNULA ANTILLARUM) NESTING ON THE MISSOURI RIVER

Abstract

Reservoir management on the Missouri River has changed the flow regime that once created dynamic emergent sandbar habitat (ESH) for the interior least tern (Sternula antillarum) and piping plover (Charadrius melodus). High flows that create large amounts of ESH are now rare, but the remaining interannual variability in river stage has strong effects on the amount of ESH available for nesting shorebirds. The scarcity of habitat has led the United States Army Corps of Engineers to develop an adaptive management plan for the restoration of ESH to support nesting terns and plovers. We describe the stochastic simulation models of ESH, plover populations and tern populations used in the adaptive management process, and examine the effects of river flow on projected outcomes of habitat restoration. The population models are most sensitive to uncertainty in adult survival rates. Model validation against historical amounts of ESH and population sizes suggests the model is a reasonable predictor of future dynamics. Flow variability contributes as much uncertainty as parameter estimation error to plover model projections but negligible uncertainty to the tern model. Autocorrelation in flow between years has stronger effects on population outcomes than the intensity of habitat restoration effort does. We compared population outcomes after a habitat-creating flow with population outcomes following habitat restoration and found that large pulses of habitat creation produced similar or better outcomes in the short term than low but consistent habitat restoration. However, bird populations fared better in the long term with low levels of restoration when habitat-forming flows were rare.

Streamflow, Sediment Transport, and Geomorphic Change during the 2011 Flood on the Missouri River Near Bismarck–Mandan, ND

“…; Buenau et al. ). Pre‐dam flows have been demonstrated to have greater variation in flow and therefore the resulting sediment transport dynamics were more spatially variable leading to greater channel complexity.…”

“…; Buenau et al. ). In the Missouri River channel, changes in depositional patterns have been documented to limit shallow water habitat in sections of the river (Skalak et al.…”

Flood Effects Provide Evidence of an Alternate Stable State from Dam Management on the Upper Missouri River

“…Historically, channel islands have been a critical habitat for the Interior Least Tern and the Piping Plover to nest. They prefer bare sand patches of medium, well‐sorted sand (Catlin et al ., ; Anteau et al ., ; Buenau et al ., ). Skalak et al .…”

“…Historically, channel islands have been a critical habitat for the Interior Least Tern and the Piping Plover to nest. They prefer bare sand patches of medium, well-sorted sand (Catlin et al, 2011;Anteau et al, 2012;Buenau et al, 2014). Skalak et al (2013) demonstrate that channel islands are being eroded in the reach immediately below the dam.…”

Multi-scale Approach to Hydrological Classification Provides Insight to Flow Structure in Altered River System

“…The restriction of the low-flow unit to the central Platte River has likely contributed to the state transition of the central Platte from an open braided system to one with maintained island complexes, decreased number and size of sandbar habitats, incised channels and dense riparian vegetation (Johnson, 1994). These changes in habitat quality and quantity have likely led to population responses in both fish and birds including decreased distribution (Peters and Schainost, 2005;Hamel et al, 2016) and changes in demographic rates (Buenau et al, 2014). The combination of anthropogenic alteration, alternating climate patterns and geomorphic discontinuities likely drives the presence and persistence of unique flow units between the central and lower Platte Rivers and may facilitate changes in ecological function and structure therein.…”