Pond Counts Research Articles

Ecological and anthropogenic drivers of waterfowl productivity are synchronous across species, space, and time.

Knowledge of interspecific and spatiotemporal variation in demography-environment relationships is key for understanding the population dynamics of sympatric species and developing multispecies conservation strategies. We used hierarchical random-effects models to examine interspecific and spatial variation in annual productivity in six migratory ducks (i.e., American wigeon [Mareca americana], blue-winged teal [Spatula discors], gadwall [Mareca strepera], green-winged teal [Anas crecca], mallard [Anas platyrhynchos] and northern pintail [Anas acuta]) across six distinct ecostrata in the Prairie Pothole Region of North America. We tested whether breeding habitat conditions (seasonal pond counts, agricultural intensification, and grassland acreage) or cross-seasonal effects (indexed by flooded rice acreage in primary wintering areas) better explained variation in the proportion of juveniles captured during late summer banding. The proportion of juveniles (i.e., productivity) was highly variable within species and ecostrata throughout 1961-2019 and generally declined through time in blue-winged teal, gadwall, mallard, pintail, and wigeon, but there was no support for a trend in green-winged teal. Productivity in Canadian ecostrata declined with increasing agricultural intensification and increased with increasing pond counts. We also found a strong cross-seasonal effect, whereby more flooded rice hectares during winter resulted in higher subsequent productivity. Our results suggest highly consistent environmental and anthropogenic effects on waterfowl productivity across species and space. Our study advances our understanding of current year and cross-seasonal effects on duck productivity across a suite of species and at finer spatial scales, which could help managers better target working-lands conservation programs on both breeding and wintering areas. We encourage other researchers to evaluate environmental drivers of population dynamics among species in a single modeling framework for a deeper understanding of whether conservation plans should be generalized or customized given limited financial resources.

Using integrated population models to prioritize region-specific conservation strategies under global change

Accounting for the spatial variation of environmental drivers and demographic mechanisms in population predictions is essential for conservation prioritization under climate and land use changes but is often ignored. We developed an integrated population model (IPM) with region-specific population processes and used the model to prioritize region-specific conservation strategies for northern pintail (Anas acuta; hereafter pintail). Pintail are of high conservation concern in North America due to low productivity related to extensive use of cropland for nesting and wetland (pond) loss related to anthropogenic disturbance and climatic variability. We analyzed 25 years (1990–2014) of pintail breeding population survey, band-recovery, pond count, climate and land use data to estimate regional demography-environment relationships. We then predicted regional population responses under potential future changes in climate, wetland drainage, and agricultural intensification. Our IPM predicted that pintail populations will be sensitive to climate changes throughout the entire study area. Drainage was predicted to have more deleterious impacts in Parkland regions due to more extensive wetland drainage in these regions. Agricultural intensification was predicted to have more deleterious impacts in Saskatchewan-Prairie due to a stronger response of pintail productivity to agricultural intensification in this region. Our study highlights the importance of considering region-specific conservation strategies to accommodate regional variation in future global changes and demographic response to such changes. Our IPM that accommodates spatial variation in environmental changes and demographic responses is flexible for other systems, and thus is highly relevant to diverse studies in conservation prioritization given global change.

On the use of remote sensing to map the proliferation of aquaculture ponds and to investigate their effect on local climate, perspectives from the Claise watershed, France.

Ponds, as landscape features, are known to regulate climate. Since ponds proliferate or recede due to natural or anthropogenic factors, a variation of pond numbers implies a variation of their climatic effect. Accordingly, this study investigates the impact of ponds on the local climate of the French Claise watershed. The latter was chosen because it contains a pond dense zone and a pondless zone. This repartition makes the Claise an adequate context to reveal the climatic impact of ponds even in the same landscape. To study the pond-climate effect, the parallel evolution of pond numbers variation and subsequent climatic impact must be tracked. Therefore, the remote sensing-derived Normalized Difference Water Index (NDWI) was extracted from LANDSAT images with different acquisition dates to track changes in pond numbers with time. When compared with a pond map established from aerial photography interpretation, the LANDSAT NDWI map revealed an accuracy of 85.74% for pond count and 75% for pond spatial allocation. This validation showed that NDWI is suitable for mapping the proliferation of ponds through time. In order to study the parallel evolution of the climatic effect, the land surface temperature (LST) index was extracted for each LANDSAT map. LST maps revealed that as a result of pond number variation, surface temperatures varied accordingly. A comparison of air temperatures between the ponded zone and pondless zones also revealed that pond zones had lower air temperatures than their direct surroundings. Accordingly, ponds were shown to buffer local microclimates even within the same landscape.

A predictive model for seasonal pond counts in the United States Prairie Pothole Region using large-scale climate connections

The Prairie Pothole Region (PPR), located in central North America, is an important region hydrologically and ecologically. Millions of wetlands, many containing ponds, are located here, and they serve as habitats for various biota and breeding grounds for waterfowl. They also provide carbon sequestration, sediment and nutrient attenuation, and floodwater storage. Land modification and climate change are threatening the PPR, and water and wildlife managers face important conservation decisions due to these threats. We developed predictive, multisite forecasting models using canonical correlation analysis (CCA) for pond counts in the southeast PPR, the portion located within the United States, to aid in these important decisions. These forecast models predict spring (May) and summer (July) pond counts for each region (stratum) of the United States Fish and Wildlife Service’s pond and waterfowl surveys using a suite of antecedent, large-scale climate variables and indices including 500 millibar heights, sea surface temperatures (SSTs), and Palmer Drought Severity Index (PDSI). Models were developed to issue forecasts at the start of all preceding months beginning on March 1st. The models were evaluated for their performance in a predictive mode by leave-one-out cross-validation. The models exhibited good performance (R values above 0.6 for May forecasts and 0.4 for July forecasts), with performance increasing as lead time decreased. This simple and versatile modeling approach offers a robust tool for efficient management and sustainability of ecology and natural resources. It demonstrates the ability to use large-scale climate variables to predict a local variable in a skilful way and could serve as an example to develop similar models for use in management and conservation decisions in other regions and sectors of the environment.

Land-use change increases climatic vulnerability of migratory birds: Insights from integrated population modelling.

Knowledge of land-use patterns that could affect animal population resiliency or vulnerability to environmental threats such as climate change is essential, yet the interactive effects of land use and climate on demography across space and time can be difficult to study. This is particularly true for migratory species, which rely on different landscapes throughout the year. Unlike most North American migratory waterfowl, populations of northern pintails (Anas acuta; hereafter pintails) have not recovered since the 1980s despite extended periods of abundant flooded wetlands (i.e. ponds). The mechanisms and drivers involved in this discrepancy remain poorly understood. While pintails are similar to other ducks in their dependence on ponds throughout their annual cycle, their extensive use of croplands for nesting differentiates them and makes them particularly vulnerable to changes in agricultural land use on prairie breeding grounds. Our intent was to quantify how changes in land use and ponds on breeding grounds have influenced pintail population dynamics by developing an integrated population model to analyse over five decades (1961-2014) of band-recovery, breeding population survey, land-use and pond count data. We focused especially on the interactive effects of pond counts and land use on pintail productivity, while accounting for density-dependent processes. Pintail populations responded more strongly to annual variation in productivity than survival. Productivity was positively correlated with pond count and negatively correlated with agricultural intensification. Further, a positive interaction between pond count and agricultural intensification was insufficient to overcome the strong negative effect of agricultural intensification on pintail productivity across nearly all pond counts. The interaction also indicated that pintail populations were more negatively impacted by the decrease in ponds associated with climate change under higher agricultural intensification. Our results indicate that pintail populations have become more vulnerable to climate change under intensified land use, which suggests that future conservation strategies must adapt to these altered relationships. The interactive effects of land use and climate on demography should be considered more frequently in animal ecology, and integrated population models provide an adaptable framework to understand vital rates and their drivers simultaneously.

Coastal Wetland Geomorphic and Vegetative Change: Effects of Sea-Level Rise and Water Management on Brackish Marshes

Conservation and management of coastal ecosystems require an understanding of how accelerated sea-level rise (SLR) and altered hydrology impact community shifts over time. This study evaluates the response of tidal wetlands of the Ten Thousand Islands, Collier County, Florida, to SLR and water management, with a focus on the development and distribution of tidal ponds across a wetland landscape. Sediment cores collected from marshes, mangroves, and tidal ponds reveal a clear transgressive stratigraphy. Facies analyses demonstrate that ponds originate from the surface downward through the degradation of marsh peat. Analyses of 1953 and 2009 aerial imagery using ArcGIS® software clearly identified tidal pond initiation, growth, and merger over time. Wetlands west of the Faka Union Canal, which have limited freshwater sheet flow due to canalization, are experiencing a greater increase in pond count, pond density (p = 0.0038), and mean pond area (p < 0.0001). Qualitative observations also recognize a relatively larger influence of mangrove envelopment over time in western sites compared with those retaining near-natural flows. Future land management plans must account for the expected submergence of inland marsh ecosystems driven by SLR and accelerated by hydrologic alteration. Continued restoration of freshwater sheet flow is necessary for slowing the regional transition (and loss) of graminoid marshes to either mangrove or pond environments. Without such action, a complete loss of these biologically diverse marsh ecosystems as mangrove forests encroach and marsh surfaces submerge is probable in the short term.

Temporal and multi-spatial environmental drivers of duck nest survival

ABSTRACT Nest survival is determined in part by a combination of large-scale environmental factors and local nest-site characteristics. Because predation is the primary cause of nest failure, those drivers likely operate by influencing predator abundance, behavior, and/or nest detectability. For example, fluctuations in landscape productivity have the potential to alter predator and prey abundance, whereas nest vegetation and patterns of nest spacing may influence predator behavior. We used 8 yr of site-specific environmental data coupled with data collected from 11,547 duck nests to evaluate the relative importance of large-scale and local factors on nest survival. We found that higher values of gross primary productivity, basins, and pond counts were associated with higher nest survival in a given year, but were associated with lower nest survival the following 2 yr. Taken in combination with the literature, our interpretation is that productive environmental conditions can result in time-lagged increas...

Waterfowl conservation in the US Prairie Pothole Region: confronting the complexities of climate change.

The Prairie Pothole Region (PPR) is the most important waterfowl production area in North America. However, waterfowl populations there are predicted to decline because of climate-related drying of wetlands. Consequently, changes in the geographic focus of PPR waterfowl conservation have been recommended, which could have long-lasting and costly impacts. We used a 40-year dataset of pond counts collected in the PPR to test hypotheses about climate-related drying. We assessed May (1974–2013) and July (1974–2003) pond numbers in 20 waterfowl survey strata to determine if trends in pond numbers were consistent with predictions of drying. We also assessed trends in precipitation and temperature for the 20 strata and developed models describing May pond numbers from 1974 through 2010 as a function of precipitation, temperature, the previous year’s pond numbers, and location. None of the 20 strata showed significant declines in May pond numbers, although seven strata showed increases over time. July pond numbers declined significantly in one stratum, and increased in seven strata. An index to hydroperiod showed significant increasing trends in three strata, and no strata had decreasing trends. Precipitation increased significantly in two strata and decreased in two from 1974 to 2010; no strata showed significant changes in temperature. The best linear model described pond numbers within all strata as a function of precipitation, temperature, the previous year’s pond numbers, and the latitude and longitude of the stratum, and explained 62% of annual variation in pond numbers. We hypothesize that direct effects of climate change on prairie pothole wetlands and waterfowl may be overshadowed by indirect effects such as intensified land use and increased pressure to drain wetlands. We recommend that an adaptive, data-driven approach be used to resolve uncertainties regarding direct and indirect effects of climate change on prairie wetlands and waterfowl, and guide future conservation efforts.

Landscape heterogeneity and the effect of environmental conditions on prairie wetlands

Populations can vary considerably in their response to environmental fluctuations, and understanding the mechanisms behind this variation is vital for predicting effects of environmental variation and change on population dynamics. Such variation can be caused by spatial differences in how environmental conditions influence key parameters for the species, such as availability of food or breeding grounds. Knowing how these differences are distributed in the landscape allows us to identify areas that we can expect the highest impact of environmental change, and where predictions on population dynamical effects will be most precise. We evaluated how wetland dynamics in the North-American prairies (pond counts; a key parameter for several waterfowl populations) were related to spatial and temporal variation in the environment, as measured by weather variables, primary productivity and phenology derived from annual normalized difference vegetation index (NDVI) curves, and agricultural composition of the landscape. Spatial and temporal variation in pond counts were closely related to these environmental variables. However, correlation strength and predictive ability of these environmental variables on wetland dynamics varied considerably across the study area. This variation was related to landscape characteristics and to the spatial scaling of the wetland dynamics, such that areas with late onset of spring, low spring temperature, high primary productivity, and high proportion of cropland had more predictable and spatially-homogenous dynamics. The success of predicting environmental influences on wetlands from NDVI measures derived from satellite images indicates they will be useful tools for assessing effects of changing landscape and climatic conditions on wetland ecosystems and their wildlife populations.

Spatial synchrony of prairie ducks: roles of wetland abundance, distance, and agricultural cover

Populations exhibit spatial synchrony when their numbers rise and fall in concert at several sites over their distribution. I examined the relationship between synchrony, abundance of wetlands (ponds), distance, and agricultural cover using count data of ten duck species counted in 23 aerial survey strata on the mid-continental prairies of North America. Expansion of agriculture may have resulted in increased synchrony of duck populations through increased foraging efficiency of nomadic predators and/or if the homogenization of nesting habitat has removed habitat features that allow differential local responses to large-scale population drivers such as precipitation. As a measure of synchrony, I calculated all pair-wise cross-correlation coefficients based on population growth rates (rt) at each survey stratum, and then regressed these correlation coefficients against measures of cross-correlation of pond (wetland) counts, distance between strata, and mean percent area of strata seeded to row crops. Synchrony for most species was most strongly related to synchrony of wetland availability among sites, and decreased with distance between sites. Synchrony of ducks that nest over water showed little effect of agricultural cover, whereas the effect of agricultural cover on synchrony of upland nesting ducks differed by species. Mobile large-bodied species showed evidence of increased synchrony due to agricultural cover, whereas smaller-bodied, more philopatric species showed evidence of decreased synchrony due to agricultural cover.

Historic and Current Status of the American White Pelican Breeding at Chase Lake National Wildlife Refuge, North Dakota

Chase Lake National Wildlife Refuge currently supports the largest breeding colony of the American White Pelican (Pelecanus erythrorhynchos) in North America. The first written account of the colony's status was in 1905, when approximately 500 pelicans nested on two islands in Chase Lake. The colony grew to nearly 34,000 breeding birds by 2002. Surveys of breeding pelicans in the colony were sporadic from 1905 until 1972. Because the availability of foraging areas affects recruitment, pond counts from south-central North Dakota were used as an index of the relative availability of foraging areas. Pond counts varied widely in the 1970s and 1980s. In 1993, pond numbers increased dramatically, reached a peak in 1997, then declined but remained relatively high through 2002. Pelican numbers also increased in the mid- to late-1990s, possibly in response to increased and stable foraging opportunities. Because rising water in Chase Lake inundated the original nesting islands during that period, pelicans were forced to relocate nesting areas. Relocation provided more nesting space than the original islands, and nesting pelicans seemed to be gradually filling these areas. Threats to the Chase Lake breeding colony include disease, predation, and human disturbance. Research is needed to better understand the mechanisms that underlie the dynamics of AWPE metapopulations and their sub-units, including factors that influence nest-site selection, productivity, and survival of adults and young in large colonies.

Differences in distribution of modified basins and ducks relative to roadside transects

Wetland basins in the Prairie Pothole Region of the U.S. are commonly modified by excavation (e.g., roadside ditches, stock dugouts), partial drainage (ditching), and diking. Differences in the distribution of modified wetlands may affect the predictive accuracy of waterfowl survey data if such wetlands are not distributed randomly in the landscape and if waterfowl are not distributed equally among them. We used data collected on thirty-eight 40-km2 plots in North Dakota to examine the distribution of modified basins relative to roadside transects and their use by five species of dabbling ducks in 1995. The 800-m-wide transects were subdivided into an inner 400-m transect, centered on the road, and the remaining outer transect area. We compared the distribution of modified and natural wetland basins among three sample areas: 1) the inner 400-m-wide roadside transect area, 2) the outer transect area, and 3) the remaining area within the 40-km2 plot that was outside of the transects (outer plot). Duck use was compared between the two transect areas. The plots contained 20,582 basins, of which 88.5% were unmodified, 7.5% were excavated, 3.7% were partially drained, and 0.2% were diked. Nearly all excavated temporary (89%) and seasonal (90%) basins occurred in the inner transect area, reflecting the high proportion of basins that would be defined as roadside ditches. Excavated semipermanent basins were more evenly distributed among the outer plot and two transect widths; these basins often were dugouts but also included roadside ditches. Partially drained and diked basins also were fairly evenly distributed among the three sample areas. Semipermanent basins had greater use by mallards (Anas platyrhynchos) and northern pintails (A. acuta) when they were partially drained than when they were excavated or unmodified; pintails also had greater use of partially drained seasonal basins. Use of wetland basins by gadwall (A. strepera), blue-winged teal (A. discors), and northern shovelers (A. clypeata) did not differ among water regimes or modification. We found no evidence to indicate that duck numbers determined from standard 400-m-wide roadside transects were biased relative to the larger landscape. However, pond counts derived from such transects were biased. Correlations of duck numbers to pond counts that exclude ditches or temporary basins would poorly reflect the response of ducks to available water.

Empirical relationships between watershed characteristics and coho salmon (Oncorhynchus kisutch) smolt abundance in 14 western Washington streams

We assembled data on coho salmon (Oncorhynchus kisutch) from 14 streams in western Washington, including annual smolt counts and annual escapement, either as absolute counts or as an index. We also compiled data on large woody debris (number·km%#150;1 of stream), road densities in the watersheds (km road·km%#150;2), gradient of the streams (%), valley slope adjacent to the stream (%), drainage area in the watershed (km2), and pool, pond, and lake areas (m2·km%#150;1). We explored the relationships between habitat variables and two measures of coho production, the maximum production of smolts in the stream (capacity) and the maximum smolts/spawner (productivity). Using the 11 streams with pool and pond counts, we found that pool and pond densities served as good predictors of smolt density (r2 = 0.85 for pools and 0.68 for ponds, independently). Pools produced 0.39 smolts·m%#150;2 and ponds produced 0.07 smolts·m%#150;2 in the multiple regression fit, accounting for 92% of the residual error. We also found that lower valley slopes, lower road densities, and lower stream gradients were correlated with higher smolt density.

Improving Prairie Pond Counts with Aerial Video and Global Positioning Systems

Technological advances in tools available for habitat surveys have occurred since the inception of the Aerial Waterfowl Breeding Ground Population and Habitat Surveys in North America (BGS). We developed a method using aerial video, a global positioning system (GPS), and an optical disk recorder to assess pond numbers in the Prairie Pothole Region. We analyzed low altitude near infrared video for 12 air-ground segments and 30 29-km transect segments that are part of the annual BGS in southern Saskatchewan. Video interpretation was done with a combination of manual and automated procedures. Average omission and commission errors for the 12 air-ground segments were 0.21 and 0.22, respectively. Estimating omission and commission errors was confounded by changes in the presence and level of water between dates of video and ground BGS. Use of GPS automated the organization of the video by transect segment on the optical disk recorder, thus reducing labor required to process video images. The time required to interpret the number of ponds for a 0.2- x 29-km transect segment ranged from 9 to 59 minutes and varied with pond abundance, size, and contrast with background. The system enabled a rapid and accurate assessment of the average number of ponds. Video imagery can be used to estimate other habitat attributes (e.g., pond area) and is a valuable source of data for analysis of habitat trends.

The Effects of Weather on Local Wood Duck Production

The U.S. Fish and Wildlife Service annually considers weather to predict waterfowl production, vis-a-vis precipitation and pond counts on the prairies and snow conditions in the Arctic, but the effects of weather on cavity nesting species such as wood ducks (Aix sponsa) is generally overlooked. This paper documents the effects of unusual weather during 1982 on wood duck production in Massachusetts.