Effects of territorial status and life history on Sandhill Crane (Antigone canadensis) population dynamics in south-central Wisconsin, USA

Abstract

Population growth rate in long-lived bird species is often most sensitive to changes in adult survival. Sandhill Cranes (Antigone canadensis (Linnaeus, 1758)) have long life spans, small broods, and delayed first reproduction. Only territorial adult Sandhill Cranes participate in breeding, and territory acquisition reflects the interplay between the availability of suitable territories and the variation in mortality of adult birds occupying those territories. We estimated vital rates of a population at equilibrium using long-term resightings data (2000–2014; n = 451 marked individuals) in a multistate mark–resight model and used a stage-structured projection matrix to assess how strongly territorial adult survival affects population growth rate. Elasticity analysis indicated territorial birds surviving and retaining territories had a 2.58 times greater impact on population growth compared with the next most important transition rate (survival of nonterritorial adults remaining nonterritorial). Knowing how changes in vital rates of various stage classes will differentially impact population growth rate allows for targeted management actions including encouraging growth in recovering populations, assessing opportunity for recreational harvest, or maintaining populations at a desired level. This study also highlights the value of collecting demographic data for all population segments, from which one can derive reproductive output or growth rate.

The reproductive success of sandhill cranes in midwestern landscapes

“…Littlefield ( a,b, ), for example, reported 49% average annual nesting success in Oregon, whereas our overall nest success was 57.5%. The findings of this and other Midwestern studies (Wheeler et al ) suggest that cranes can successfully breed in urban areas and that those areas offer suitable nesting and foraging sites. The use of urban landscapes appears to contribute to the continued population expansion of sandhill cranes.…”

“…Littlefield (1995aLittlefield ( ,b, 2003, for example, reported 49% average annual nesting success in Oregon, whereas our overall nest success was 57.5%. The findings of this and other Midwestern studies (Wheeler et al 2019) suggest that cranes can successfully breed in urban areas Table 2. Model ranks for nest survival for sandhill cranes, defined as the probability that ≥1 egg survived to hatch.…”

“…Although the increase in cranes in urban areas will facilitate the continued recovery of this population, it will also likely lead to more crane‐human conflicts (Barzen and Ballinger ). Given the relatively high productivity of cranes in urban landscapes, we expect that crane habitat in urban areas will become saturated as it has in more rural areas of its breeding range (Wheeler et al ).…”

Applying hierarchical resource selection concepts to solving crop damage caused by birds

“…We measured crane use of agricultural and nonagricultural areas along three routes within the study area in all six study years and followed the protocol of previous studies (Barzen et al, 2018; McKinney et al, 2016; Wheeler et al, 2019). Each route surrounded a large wetland in the Neenah and Widow Green Creek basins (Barzen et al, 2016) and was surveyed six times a day.…”

“…In addition, crane damage has lacked effective solutions (Barzen & Ballinger, 2017). Further, we had an ongoing long‐term field project in an area where damage was occurring which allowed ecological contexts of habitat, social and population dynamics to be understood (e.g., Hayes, 2015; Su, 2003; Wheeler, Barzen, & Crimmins, 2019). To our knowledge, this study represents a rare approach for solving avian damage to crops at a landscape level (Treves et al, 2006).…”