Population estimates for tidal marsh birds of high conservation concern in the northeastern USA from a design-based survey

Influence of call broadcast timing within point counts and survey duration on detection probability of marsh breeding birds

“…When estimating occupancy or population size within a certain area, occurrences or counts from only the passive period rather than all of the periods within point counts are typically used as the response variable (e.g., Wiest et al 2016). This is because individuals may be drawn closer to the observer by broadcasts before they become available for detection, which might make occupancy and density estimates biased because the effective survey area is uncertain (Conway 2011).…”

“…Broadcast bias includes drawing broadcast species closer to the observer before they become available for detection, i.e., before they vocalize or become visible, and increased difficulty in hearing nonbroadcast species during the broadcast period (Conway and Gibbs 2005). These sources of bias can be problematic when determining densities and associated population sizes (e.g., Wiest et al 2016).…”

How will sea-level rise affect threats to nesting success for Seaside Sparrows?

“…The conservation implications of this finding are stark: nest survival rates could become very low, perhaps so low as to preclude the production of any young within a subpopulation's breeding season, especially during years with both high flooding and predation risk. To better estimate this possibility, more investigation into the links and feedbacks among Seaside Sparrow population size, individuals' behaviors, predator populations, and tidal conditions is warranted, with a potential first step being the establishment of long-term monitoring sites similar to those in the northeastern United States (Wiest et al 2016). However, given the results of the present study and of others showing high vulnerability of Seaside Sparrows to SLR (Kern andShriver 2014, Hunter et al 2016a), it is likely that in the coming decades, management actions (in conjunction with continued research on the population) will be necessary to maintain population viability.…”

A test of a corollary of Allen's rule suggests a role for population density

“…They do, however, still possess larger bills on average than their closest non-tidal-marsh relative (Shriver et al 2011, Greenlaw et al 2018, which is the convergent pattern across a large suite of coastal birds (Grenier andGreenberg 2005, Luther andGreenberg 2011). Importantly, however, saltmarsh sparrows also possess variation in breeding density independent of the temperature cline, as density is highest in the range center (Wiest et al 2016, Field et al 2018. Importantly, however, saltmarsh sparrows also possess variation in breeding density independent of the temperature cline, as density is highest in the range center (Wiest et al 2016, Field et al 2018.…”

“…From 2010 to 2012, we captured adult saltmarsh and Nelson's sparrows in 31 marshes across a latitudinal range that includes 66% of the estimated saltmarsh sparrow breeding birds (Wiest et al 2016) and the very southern end of the breeding range of the Atlantic subspecies of the Nelson's sparrow A. nelsoni subvirgata. Capture locations were in high-marsh habitat (variously dominated by Spartina patens, short-form S. alterniflora, Distichlis spicata and Juncus gerardii) and provided replication both across the range and within watersheds to reflect local habitat heterogeneity.…”