Browsing by Author "Hunt, Kelsi L."

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    Atlantic Flyway Disturbance Project Phase 2: Biological Data Collection Report
    Gibson, Daniel; Hunt, Kelsi L.; Catlin, Daniel H. (2021)
    Human disturbance is a significant threat facing shorebirds throughout the annual cycle, and threats to shorebird habitats may be exacerbated by increased human use (e.g., beach recreationists, off-leash dogs), reducing the amount of coastal habitat that is functionally available to shorebirds. We worked with partners across the Atlantic flyway to develop a standardized protocol for data collection to evaluate the effects of human disturbance on six Atlantic Flyway Shorebird Initiative (AFSI) focal species (American Oystercatchers [AMOY; Haematopus palliates], Piping Plovers [PIPL; Charadrius melodus], Red Knots [REKN; Calidris canutus], Sanderling [SAND; Calidris Alba], Semipalmated Sandpipers [SESA; Calidris pusilla], and Wilson’s Plovers [WIPL; Charadrius wilsonia]).
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    Direct and indirect effects of nesting density on survival and breeding propensity of an endangered shorebird
    Catlin, Daniel H.; Gibson, Daniel; Hunt, Kelsi L.; Friedrich, Meryl J.; Weithman, Chelsea E.; Karpanty, Sarah M.; Fraser, James D. (ESA, 2019-04-08)
    Density-dependent regulation is a fundamental part of ecological theory and a significant driver of animal demography often through complex feedback loops. We investigated the relationship between flood- and demographically induced fluctuations in density and the breeding propensity and survival of a pioneer species, the piping plover (plover, Charadrius melodus).We captured and marked adult and hatchling plovers on the Gavins Point Reach of the Missouri River in South Dakota and Nebraska, USA, from 2005 to 2014. In 2010 and 2011, historically high water levels and flooding inundated much of the plover’s sandbar nesting habitat on theMissouri River.We developed a Bayesian formulation of a multievent model, or a multistate survival model with state uncertainty to estimate breeding propensity simultaneously with survival. Although plovers are conspicuous, their breeding status can be difficult to establish with certainty, which necessitated the use of uncertain states.With this model, we investigated the effect of sex, habitat availability, river flow, and density (birds/ha nesting habitat) on survival of hatch year and breeding and non-breeding adult plovers. In addition, we estimated the transition rates for these age classes between breeding and nonbreeding states. Non-breeding adults (ɸAHY, n = 0.58 ± 0.06) had lower survival rates than breeding adults (ɸAHY, b = 0.80 ± 0.04), and both breeding survival and breeding propensity decreased with increasing nesting density. Not only did survival and breeding propensity decrease directly at higher nest densities, but survival also was indirectly impacted by increasing the proportion of non-breeding birds with relatively low survival. Thus, plovers were regulated through a complex set of feedback loops, acting as densities increased. Our findings underscore the intricacy of density-dependent regulation and suggest that detailed demographic studies are needed to fully understand these effects.
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    Effects of climate change and anthropogenic modification on a disturbance-dependent species in a large riverine system
    Zeigler, Sara L.; Catlin, Daniel H.; Brown, Mary Bomberger; Fraser, James D.; Dinan, Lauren R.; Hunt, Kelsi L.; Jorgensen, Joel G.; Karpanty, Sarah M. (Ecological Society of America, 2017-01)
    Humans have altered nearly every natural disturbance regime on the planet through climate and land-use change, and in many instances, these processes may have interacting effects. For example, projected shifts in temperature and precipitation will likely influence disturbance regimes already affected by anthropogenic fire suppression or river impoundments. Understanding how disturbance-dependent species respond to complex and interacting environmental changes is important for conservation efforts. Using field-based demographic and movement rates, we conducted a metapopulation viability analysis for piping plovers (Charadrius melodus), a threatened disturbance-dependent species, along the Missouri and Platte rivers in the Great Plains of North America. Our aim was to better understand current and projected future metapopulation dynamics given that natural disturbances (flooding or high-flow events) have been greatly reduced by river impoundments and that climate change could further alter the disturbance regime. Although metapopulation abundance has been substantially reduced under the current suppressed disturbance regime (high-flow return interval similar to 20 yr), it could grow if the frequency of high-flow events increases as predicted under likely climate change scenarios. We found that a four-year return interval would maximize metapopulation abundance, and all subpopulations in the metapopulation would act as sources at a return interval of 15 yr or less. Regardless of disturbance frequency, the presence of even a small, stable source subpopulation buffered the metapopulation and sustained a low metapopulation extinction risk. Therefore, climate change could have positive effects in ecosystems where disturbances have been anthropogenically suppressed when climatic shifts move disturbance regimes toward more historical patterns. Furthermore, stable source populations, even if unintentionally maintained through anthropogenic activities, may be critical for the persistence of metapopulations of early-successional species under both suppressed disturbance regimes and disturbance regimes where climate change has further altered disturbance frequency or scope.
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    Habitat selection and potential fitness consequences of two early‐successional species with differing life‐history strategies
    Catlin, Daniel H.; Gibson, Daniel; Friedrich, Meryl J.; Hunt, Kelsi L.; Karpanty, Sarah M.; Fraser, James D. (Wiley, 2019-11-19)
    Habitat selection and its relationship to fitness is a fundamental concept in ecology, but the mechanisms driving this connection are complex and difficult to detect. Despite the difficulties in understanding such intricate relationships, it is imperative that we study habitat selection and its relationship with fitness. We compared habitat selection of least terns (Sternula antillarum) and piping plovers (Charadrius melodus) on the Missouri River (2012–2014) to examine the consequences of those choices on nest and chick survival. We hypothesized that plovers and terns would select habitat that minimized the chance of flooding and predation of eggs, chicks, and adults, but that plovers would also select habitat that would provide foraging habitat for their chicks. We developed an integrated habitat selection model that assessed selection across multiple scales (sandbar and nest scales) and directly modeled the effect of selection on nest and chick survival. In general, the species selected habitat in keeping with our hypotheses, such that predation and flooding, in particular, may have been reduced. Sandbar selection had either a negative or no appreciable effect on nest survival for both species across years. Nest‐site selection in 2012 had a generally positive effect on nest survival and chick survival for both terns and plovers, and this trended toward a negative effect by 2014. This result suggested that early selection decisions appeared to be adaptive, but we speculate that relatively high site fidelity and habitat degradation led to reduced benefit over time. Our results highlight the complex nature of habitat selection and its relationship to fitness.
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    Management and Mother Nature: piping plover demography and condition in response to flooding on the Missouri River
    Hunt, Kelsi L. (Virginia Tech, 2016-11-17)
    Globally, riparian ecosystems are in decline due to anthropogenic modifications including damming, channelization and the conversion of the floodplain for human use. These changes can profoundly affect riparian species as many have adapted to the historical dynamism of these ecosystems. On the managed Missouri River, an imperiled shorebird, the piping plover (Charadrius melodus) uses riverine sandbars to breed. From 2004 to 2009, due to limited breeding habitat and low population numbers, the U.S. Army Corps of Engineers constructed 255 ha of sandbar habitat to benefit piping plovers and least terns (Sternula antillarum). During the breeding seasons of 2010 and 2011, historically high flows resulted in the creation of 1,887 ha of suitable sandbar habitat. Our study compared the demographic response and the condition of piping plovers to these anthropogenic and natural habitat creation events. From 2005–2014 we monitored 1,071 nests, and from those nests we uniquely banded 968 adults and 2,021 piping plover chicks. We obtained 405 egg (clutch) mass measurements, 1,285 mass measurements from 633 adults, and 7,093 mass measurements from 1,996 plover chicks resulting in 3,175 mass measurements from 654 broods of chicks. We also collected 3,347 invertebrate prey samples. We used a random effects logistic exposure model to estimate nest success, a random effects Cormack-Jolly-Seber model in RMARK to estimate pre-fledge chick survival and the Barker model in RMARK to estimate hatch-year (HY) and after hatch-year (AHY) survival and fidelity to our study area. We then used estimates from these analyses to calculate reproductive output, reproductive output necessary for a stationary population, and population growth (λ). For adult condition and egg (clutch) mass we used generalized linear mixed regression, and for pre-fledge chick growth rates we used a modified Richard's model to estimate the effects of habitat type (pre- vs. post-flood). We also tested for differences in invertebrate prey abundance between habitat types using negative binomial regression. Our results indicated that AHY survival varied throughout our study and was lowest during the flood (2010 and 2011). We found that nest success, pre-fledge chick survival, reproductive output, and HY survival and fidelity were consistently higher on the flood-created habitat than engineered habitat, leading to sustained population growth after the flooding, as compared to just one year of population growth prior to the flood. Unlike pre-flood engineered habitat, the demographic parameters we measured did not decrease as the post-flood habitat aged. These differences were related to increased sandbar habitat, low nesting densities, and decreased nest and chick predation on the post-flood habitat. Although we hypothesized that increased demographic rates would be reflected by increased piping plover condition following the flood, we found that our measured condition variables (adult mass, clutch mass, and pre-fledge chick growth rates) remained unchanged following the flood. We also found evidence that clutch mass, chick growth rates and invertebrate prey abundance decreased as the post-flood sandbar habitat aged. As the condition of individuals did not appear to contribute directly to the increased demographic rates following the flood, we suggest that the change in density-dependent predation pressure may explain the discrepancy. As many ecosystems have previously been altered, it's rare that ecologists have the opportunity to compare management practices with natural ecosystem processes. Results from this study suggest that management intervention may not be an equivalent substitute for natural ecosystem processes and provide insight on future management of riparian ecosystem.
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    Metapopulation viability of an endangered shorebird depends on dispersal and human-created habitats: piping plovers (Charadrius melodus) and prairie rivers
    Catlin, Daniel H.; Zeigler, Sara L.; Brown, Mary B.; Dinan, Lauren R.; Fraser, James D.; Hunt, Kelsi L.; Jorgensen, Joel G. (2016-03-15)
    Background Many species are distributed as metapopulations in dynamic landscapes, where habitats change through space and time. Individuals locate habitat through dispersal, and the relationship between a species and landscape characteristics can have profound effects on population persistence. Despite the importance of connectivity in dynamic environments, few empirical studies have examined temporal variability in dispersal or its effect on metapopulation dynamics. In response to this knowledge gap, we studied the dispersal, demography, and viability of a metapopulation of an endangered, disturbance-dependent shorebird. We examined three subpopulations of piping plovers (Charadrius melodus) on the lower Platte and Missouri rivers from 2008–2013. High flow events from an upstream dam on the Missouri River in 2010 and 2011 allowed us to assess the effect of total habitat loss and the subsequent creation of new habitat associated with a large disturbance at one ‘natural’ study location. The other two sites within the metapopulation, which were maintained by anthropogenic activities (e.g., mining, development, habitat restoration), were largely unaffected by this disturbance, resulting in a controlled natural experiment. Results High flow events were associated with increased emigration, decreased immigration, and decreased survival in the subpopulation that experienced high flows. Following the high flow event, immigration into that subpopulation increased. Dispersal rates among subpopulations were negatively correlated with distance. The metapopulation had a low probability of extinction over 100 years (0 %) under the current disturbance interval and associated dispersal and survival rates. However, persistence depended on relatively stable, human-created habitats, not the dynamic, natural habitat (47.7 % extinction probability for this subpopulation). Conclusions We found that functional connectivity, as measured by the rate of dispersal among subpopulations, increased as a result of the high flow event in our study metapopulation. Plovers also increased reproductive output following this event. Although the study metapopulation had a low overall probability of extinction, metapopulation persistence depended on anthropogenically created habitats that provided a small but stable source of nesting habitat and dispersers through time. However, all subpopulations remained small, even if persistent, making them individually vulnerable to extinction through stochastic events. Given the highly dynamic nature of habitat availability in this system, maintaining several subpopulations within the metapopulation and stable sources of habitat will be critical, and this species will likely remain conservation-reliant.
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    Senescence and carryover effects of reproductive performance influence migration, condition, and breeding propensity in a small shorebird
    Weithman, Chelsea E.; Gibson, Daniel; Hunt, Kelsi L.; Friedrich, Meryl J.; Fraser, James D.; Karpanty, Sarah M.; Catlin, Daniel H. (Wiley, 2017-11-15)
    Breeding propensity, the probability that an animal will attempt to breed each year, is perhaps the least understood demographic process influencing annual fecundity. Breeding propensity is ecologically complex, as associations among a variety of intrinsic and extrinsic factors may interact to affect an animal’s breeding decisions. Individuals that opt not to breed can be more difficult to detect than breeders, which can (1) lead to difficulty in estimation of breeding propensity, and (2) bias other demographic parameters. We studied the effects of sex, age, and population reproductive success on the survival and breeding propensity of a migratory shorebird, the piping plover (Charadrius melodus), nesting on the Missouri River. We used a robust design Barker model to estimate true survival and breeding propensity and found survival decreased as birds aged and did so more quickly for males than females. Monthly survival during the breeding season was lower than during migration or the nonbreeding season. Males were less likely to skip breeding (range: 1–17%) than females (range: 3–26%; βsex = −0.21, 95% CI: −0.38 to −0.21), and both sexes were less likely to return to the breeding grounds following a year of high reproductive success. Birds that returned in a year following relatively high population-wide reproductive output were in poorer condition than following a year with lower reproductive output. Younger adult birds and females were more likely to migrate from the breeding area earlier than older birds and males; however, all birds stayed on the breeding grounds longer when nest survival was low, presumably because of renesting attempts. Piping plovers used a variety of environmental and demographic cues to inform their reproduction, employing strategies that could maximize fitness on average. Our results support the “disposable soma” theory of aging and follow with predictions from life history theory, exhibiting the intimate connections among the core ecological concepts of senescence, carryover effects, and life history.