Regional drivers of clutch loss reveal important trade-offs for beach-nesting birds

Abstract

Coastal birds are critical ecosystem constituents on sandy shores, yet are threatened by depressed reproductive success resulting from direct and indirect anthropogenic and natural pressures. Few studies examine clutch fate across the wide range of environments experienced by birds; instead, most focus at the small site scale. We examine survival of model shorebird clutches as an index of true clutch survival at a regional scale (~ 200 km), encompassing a variety of geomorphologies, predator communities, and human use regimes in southeast Queensland, Australia. Of the 132 model nests deployed and monitored with cameras, 45 (34%) survived the experimental exposure period. Thirty-five (27%) were lost to flooding, 32 (24%) were depredated, 9 (7%) buried by sand, 7 (5%) destroyed by people, 3 (2%) failed by unknown causes, and 1 (0.1%) was destroyed by a dog. Clutch fate differed substantially among regions, particularly with respect to losses from flooding and predation. 'Topographic' exposure was the main driver of mortality of nests placed close to the drift line near the base of dunes, which were lost to waves (particularly during storms) and to a lesser extent depredation. Predators determined the fate of clutches not lost to waves, with the depredation probability largely influenced by region. Depredation probability declined as nests were backed by higher dunes and were placed closer to vegetation. This study emphasizes the scale at which clutch fate and survival varies within a regional context, the prominence of corvids as egg predators, the significant role of flooding as a source of nest loss, and the multiple trade-offs faced by beach-nesting birds and those that manage them. 41 (24%) were depredated, 9 (7%) buried by sand, 7 (5%) destroyed by people, 3 (2%) failed by 42 unknown causes, and 1 (0.1%) was destroyed by a dog. Clutch fate differed substantially among 43 regions, particularly with respect to losses from flooding and predation. 'Topographic' exposure 44 was the main driver of mortality of nests placed close to the drift line near the base of dunes, 45 which were lost to waves (particularly during storms) and to a lesser extent depredation.46 Predators determined the fate of clutches not lost to waves, with the depredation probability 47 largely influenced by region. Depredation probability declined as nests were backed by higher 48 dunes and were placed closer to vegetation. This study emphasizes the scale at which clutch fate 49 and survival varies within a regional context, the prominence of corvids as egg predators, the 50 significant role of flooding as a source of nest loss, and the multiple trade-offs faced by beach-51 nesting birds and those that manage them. 5253 Several iconic, threatened species of the world's coastlines nest on ocean-exposed sandy shores 54 (e.g., turtles, birds) and are thought to use nest-site selection to increase clutch success, hatchling 55 survival, and ultimately fitness (Refsnider & Janzen 2010; Spencer 2002). Sandy shores include 56 distinct habitat types ...

Red Fox Use of Landscapes with Nesting Shorebirds

“…It is also possible that red foxes in our study area are not influenced by anthropogenic features or the levels of human presence within the study area. Maslo et al (2016) reported that predation of nests was not stronger on human‐dominated beaches, suggesting that habitat use by predators was not strongly influenced by human activity.…”

Peer Review #2 of "A comparison of sex, morphology, physiology and behavior of black-capped chickadees trapped using two common capture methods (v0.1)"

“…Results do not differ if we instead analyze each trait separately as a response variable in a linear mixed-effect model with capture method as the sole fixed effect and capture site, order of use of capture methods, and/or order of stimulus presentation (for behavioral data) as random effects. Conditional inference tree and other decision tree approaches are increasingly being used in ecological research (e.g., Johnstone, Lill & Reina, 2014;Maslo et al, 2016;Burke et al, 2020;d'Entrement et al, 2020), and can be preferable to traditional regression methods as they can allow for a more conservative, refined, and holistic approach to identifying differences among groups (Cutler et al, 2007;Müller, Schröder & Müller, 2009, Blank & Blaustein, 2014. Conditional inference trees are also powerful because of their ability to simultaneously assess categorical and continuous variables (including data with non-normal distributions) and to accommodate missing values (Hothorn, Hornik & Zeileis, 2006).…”

A Comparison of 2 Methods to Deter Fish Crows from Depredating Seabird Eggs

“…Corvids are intelligent, efficient predators that are also highly adaptable (Maslo et al 2016). Having a suite of effective methods to decrease their predation rates is important for seabird colony management.…”

“…In a quantitative assessment of the main threats to seabirds, Dias et al (2019) determined that predation from invasive alien and other problematic species are one of the greatest threats to seabird persistence. Corvids have been identified as one of the most important seabird egg predators because they are intelligent, mobile, and their density increases with proximity to humans (Maslo et al 2016). Intense corvid predation has been linked to the complete abandonment of seabird colonies (Brunton 1999, Voigts 1999, Forys et al 2015), but even moderate predation can delay nesting and decrease productivity.…”