Timing of arrival at breeding grounds determines spatial patterns of productivity within the population of white stork (Ciconia ciconia)

Early arrival at breeding grounds have important fitness consequences for migratory birds, both at individual and population level. The aim of this study was to investigate how the timing of arrival at the breeding territories affects the spatial patterns of reproductive success within a population of white storks (Ciconia ciconia). Data were gathered annually for ca. 200 pairs of storks breeding in central Poland between 1994 and 2011. Geostatistical analysis of data indicated that in years of delayed arrival of the population (measured by the first quartile arrival date), the reproductive output of storks was negatively autocorrelated, which indicated that there was a tendency for pairs of high breeding success to neighbour with pairs of low success. By contrast, in years when first storks returned in early dates to the breeding grounds, their reproductive success did not show any kind of spatial autocorrelation. These results suggest that delayed return of the first-arriving storks of the population may increase intensity of intra-specific competition to the level at which high-quality breeding pairs monopolize most of available resources at the expense of neighbouring low-quality pairs, which have lower reproductive success as a consequence. Such hypothesis was further supported with the analysis of nesting densities, showing that the late-arriving breeding pairs incurred greater fitness costs (or derived lower fitness benefits) while breeding in high densities comparatively to the early-arriving conspecifics.     

Fitness consequences of ecological constraints and implications for the evolution of sociality in an incipiently social bee

Ecological constraints such as resource limitation, unfavourable weather conditions, and parasite pressure have long been considered some of the most important selective pressures for the evolution of sociality. In the present study, we assess the fitness consequences of these three ecological factors on reproductive success of solitary nests and social colonies in the socially polymorphic small carpenter bee, Ceratina australensis, based on 982 nests collected over four reproductive periods. Nest site limitation was predicted to decrease opportunities for independent nest initiation and increase the frequency of social nesting. Nest sites were not limiting in this species and the frequency of social nesting was consistent across the four brood‐rearing periods studied. Unfavourable weather was predicted to lower the frequency of female dispersal from their natal nests and to limit the brood‐rearing season; this would increase the frequency and fitness of social colonies. Daily temperature and precipitation accumulation varied between seasons but were not correlated with reproductive success in this bee. Increased parasite pressure is predicted to increase the frequency and fitness of social colonies because solitary bees must leave the nest unattended during foraging bouts and are less able to defend the nest against parasites. Severe parasitism by a chalcid wasp (Eurytoma sp.) resulted in low reproductive success and total nest failure in solitary nests. Social colonies had higher reproductive success and were never extirpated by parasites. The high frequency of solitary nests suggests that this is the optimal strategy. However, social colonies have a selective advantage over solitary nesting females during periods of extreme parasite pressure, and we suggest that social nesting represents a form of bet‐hedging against unpredictable fluctuations in parasite number. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 57–67.     

The relationship between population means and variances of reproductive success differs between local populations of white stork (Ciconia ciconia)

We studied the size and productivity of white stork (Ciconia ciconia) populations in eight study sites in Poland. The number of nesting pairs and the average number of chicks fledged per pair fluctuated over time, and the studied populations differed in the variance of both breeding success and number of breeding pairs. The variance of breeding success (both for the mean number of chicks and the proportion of successful nests) and the variance of the number of breeding pairs was not correlated with the extent of stable habitats (pastures, meadows, wetlands), other habitats (farmland), or with local population trends over time. We found a non-linear symmetrical relationship between annual mean reproductive success and its variance but only when considered as the proportion of successful nests (i.e., when individual nests are coded as a binary value: 0, no success; 1, success). No such relationship existed when success was expressed as the number of fledged chicks. Although a positive significant correlation occurred between fledgling numbers (discrete data) and the proportion of successful nests (binary data), we believe that the use of only binary data will be inadequate in more detailed analyses, such as population viability analysis.     

Divergent seed production responses of white and blue flowers of Gentiana leucomelaena (Gentianaceae) to warming and watering

Background: The adaptation, evolution and function of flower colour diversity in response to changing environments are one of the oldest puzzles in plant ecology. It is logical that comparative studies on fitness of flower colour would be the most meaningful if they were conducted on the same genotype.

Aims: We used Gentiana leucomelaena, which produces both white and blue flowers on different tillers of the same individual, as a model species to test adaption and fitness differences of contrasting flowers in contrasting environments.

Methods: We examined seed production by white and blue flowers in response to increased temperatures (28 °C/2 °C vs. 12 °C/2 °C; 12 h light/12 h dark) in a climate chamber study and to watering in the field (+1.5 l m^?2 d^?1 vs. control with no supplementary irrigation).

Results: For white and blue flowers warming decreased but watering increased seed number. Increased temperature and watering increased the size of seeds from white flowers, but neither warming nor watering significantly changed seed size of blue flowers. Seed size was significantly negatively correlated with seed number in the temperature treatments but positively correlated in watering treatments. The positive correlation was strong in white flowers, but the negative correlation was stronger in blue than in white flowers.

Conclusions: Water availability and low temperature confer an advantage to white flowers, while warming and dry habitats favour blue flowers. These divergent responses may influence total plant fitness and thus help explain the adaptive value and evolution of flower colour diversity.     

The Influence of Parental Color Morph on Mate Choice in the Cichlid Fish Cichlasoma nigrofasciatum

Cichlasoma nigrofasciatum of two different color morphs (striped or white), each of which had been taken care of from spawning up to 7 weeks of age by foster parents of the other color morph, were put together in a “free choice situation” and tested for their preference to spawn with a mate of the striped or of the white morph. The number of pairs of the same color (striped × striped, white × white) and of different color (“mixed” pairs, striped × white) was recorded and compared with the results of control fish. The latter had been taken care of from spawning up to 7 weeks of age by foster parents of the same color morph and were also tested in a free choice situation. The influence of parental color morph on mate choice was analysed in the first mate choice of naive animals (breeding for the first time). The stability over time of the preferences observed in the naive animals was then studied in the 18 months following the first mate choice experiment. Our results show that if young Cichlasoma nigrofasciatum had been taken care of by foster parents of the other color morph, but had grown up with siblings of their own color morph, approximately 9 % of the matings involved partners which had a different color (mixed pairs). In contrast, young which had been taken care of by foster parents of their own color morph and had grown up with siblings of their own color were completely segregated according to color during breeding (striped pairs or white pairs) and never formed mixed pairs. The importance of the influence of parental and sibling color morph on the preference to mate with a particular morph and, consequently, on speciation in cichlids in general are discussed.     

Nest‐site characteristics,breeding success and competitive interactions between two recently sympatric apex predators

An influential period in avian life‐cycles is the annual breeding season, when competition over suitable nesting sites and territories is a key factor that can determine fitness and distribution, especially for species that are highly selective in their nesting habitats. We analysed nest‐site characteristics, breeding success and competitive interactions between two apex predator populations. Whereas the Short‐toed Eagle Circaetus gallicus has nested in the Judean Foothills (Israel) for a long time, the Long‐legged Buzzard Buteo rufinus has only invaded the nesting habitat of the Short‐toed Eagle during their breeding season in the last two decades. These two recently sympatric species have similar nesting ecology and frequently use the same nests. They are therefore expected to compete over nesting sites and territories. We analysed interspecific interactions between these two species by combining information from comprehensive observational, experimental, GIS analysis and remote sensing data, deriving 65 variables to characterize the nest‐sites used and the breeding success in 381 breeding attempts over four consecutive breeding seasons. To assess interspecific and intraspecific territorial behaviour and aggressiveness, stuffed Long‐legged Buzzards and Short‐toed Eagles were presented close to nests. Nest‐site characteristics overlapped substantially between species, and Long‐legged Buzzards occupied 21% of all Short‐toed Eagle nests. Intraspecific aggression rates among Long‐legged Buzzards were higher than their interspecific aggression rates with Short‐toed Eagles and also higher than intraspecific aggression among Short‐toed Eagles. Long‐legged Buzzard and Short‐toed Eagle breeding densities (1.59 ± 0.11 and 2.96 ± 0.11 pairs per 10 km², respectively) are likely to be the highest across their respective breeding distributions, with a maximum productivity of 0.96 ± 0.01 and 0.56 ± 0.05 (young fledged/breeding pair) for Long‐legged Buzzard and Short‐toed Eagle, respectively. Intraspecific interactions among both species play an important role in determining their breeding success and the spatial distribution of nesting sites. Our results suggest that interspecific competition over nesting sites and territories between both species, and the potential dominance of Long‐legged Buzzard, has both direct and indirect impacts on the spatial and demographic distribution of Short‐toed Eagles due to the recent establishment of Long‐legged Buzzard territories in the Judean breeding area.     

A model for the evolution of assortative mating

Abstract: Many animals and plants show a correlation between the traits of the individuals in the mating pair, implying assortative mating. Given the ubiquity of assortative mating in nature, why and how it has evolved remain open questions. Here we attempt to answer these questions in those cases where the trait under assortment is the same in males and females. We consider the most favorable scenario for assortment to evolve, where the same trait is under assortment and viability selection. We find conditions for assortment to evolve using a multilocus formalism in a haploid population. Our results show how epistasis in fitness between the loci that control the focal trait is crucial for assortment to evolve. We then assume specific forms of assortment in haploids and diploids and study the limiting cases of selective and nonselective mating. We find that selection for increased assortment is weak and that where increased assortment is costly, it does not invade.     

The potential for arms race and Red Queen coevolution in a protist host–parasite system

The dynamics and consequences of host–parasite coevolution depend on the nature of host genotype‐by‐parasite genotype interactions (G × G) for host and parasite fitness. G × G with crossing reaction norms can yield cyclic dynamics of allele frequencies (“Red Queen” dynamics) while G × G where the variance among host genotypes differs between parasite genotypes results in selective sweeps (“arms race” dynamics). Here, we investigate the relative potential for arms race and Red Queen coevolution in a protist host–parasite system, the dinoflagellate Alexandrium minutum and its parasite Parvilucifera sinerae. We challenged nine different clones of A. minutum with 10 clones of P. sinerae in a fully factorial design and measured infection success and host and parasite fitness. Each host genotype was successfully infected by four to ten of the parasite genotypes. There were strong G × Gs for infection success, as well as both host and parasite fitness. About three quarters of the G × G variance components for host and parasite fitness were due to crossing reaction norms. There were no general costs of resistance or infectivity. We conclude that there is high potential for Red Queen dynamics in this host–parasite system.     

Extrinsic and intrinsic factors influence fitness in an avian hybrid zone

The effects of hybridization on evolutionary processes are primarily determined by the differential between hybrid and parental species fitness. Assessing the impacts of hybridization can be challenging, however, as determining the relationship between individual fitness and the extent of introgression in wild populations is difficult. We evaluated the fitness consequences of hybridization for pure and hybrid females in a hybrid zone between two tidal marsh birds, the saltmarsh sparrow (Ammodramus caudacutus), a salt marsh obligate, and Nelson's sparrow (A. nelsoni), which has a broader ecological niche and a much younger evolutionary association with salt marshes. Biotic stressors associated with nesting in tidal environments suggest an important role for differential adaptation in shaping hybrid zone dynamics, with saltmarsh sparrows predicted to be better adapted to nesting in salt marshes. We collected DNA samples from adults (n = 394) and nestlings (n = 431) to determine the extent of introgression using 12 microsatellite loci and tested for the influence of extrinsic (nest placement) and intrinsic (genotype) factors on female reproductive success. We monitored nests (n = 228), collected data on reproductive output, and estimated daily nest survival rates using female genotype and nest characteristics as covariates. To test for reduced survival of hybrid females, we also used capture data to assess the distribution of admixed male and female individuals across age classes. Reproductive success of females varied by genotypic class, but hybrids did not have intermediate success as predicted. Instead, we found that pure Nelson's sparrows had, on average, 33% lower hatching success than any other genotype, whereas F1/F2 hybrids, backcrossed Nelson's sparrows, and backcrossed and pure saltmarsh sparrows all had similar hatching success. We found no effect of genotype or nest placement on daily nest survival probabilities. However, hybrid individuals with a higher proportion of saltmarsh sparrow alleles exhibit nesting behaviours better suited to nesting successfully in tidal marshes. Further, while the proportion of F1/F2 individuals was similar between nestling and adult males, we found that the proportion of F1/F2 individuals was 2.3 times greater in nestling females compared with adult females, indicating reduced survival of F1 females. We conclude that differences in reproductive success among pure and admixed individuals coupled with intrinsic mechanisms (reduced survival in F1 females) shape hybrid zone dynamics in this system.     

A Computer Model Allowing Maintenance of Large Amounts of Genetic Variability in Mendelian Populations. II. the Balance of Forces between Linkage and Random Assortment

It is shown, through theory and computer simulations of outbreeding Mendelian populations, that there may be conditions under which a balance is struck between two facotrs. The first is the advantage of random assortment, which will, when multilocus selection is for intermediate equilibrium values, lead to higher average heterozygosity than when linkage is introduced. There is some indication that random assortment is also advantageous when selection is toward a uniform distribution of equilibrium values. The second factor is the advantage of linkage between loci having positive epistatic interactions. When multilocus selection is for a bimodal distribution of equilibrium values an early advantage of random assortment is replaced by a later disadvantage. Linkage disequilibrium, which in finite populations is increased only by random or selective sampling, may hinder the movement of alleles to their selective equilibria, thus leading to the advantage of random assortment.-Some consequences of this approach to the structure of natural populations are discussed.     

Personality in Blue Tits (Cyanistes caeruleus) and its Effect on Their Breeding Success

In this study, we investigated whether blue tits (Cyanistes caeruleus) showed consistent variation in neophobia responses. The experiment represents a test of how personality, consistent individual differences in behaviour, may have fitness consequences. The experimental design consisted of a control observation followed by two neophobia tests, during which the parent's behaviour was recorded using the instantaneous sampling method. Blue tits showed consistent variation in neophobia responses, which was related to total offspring biomass, but not to mean offspring weight or fledging success. General linear mixed models analyses suggest that there may be ideal neophobia trait combinations in breeding pairs that maximise breeding success.     

Coherent synthesis of genomic associations with phenotypes and home environments

Local adaptation is often studied via (i) multiple common garden experiments comparing performance of genotypes in different environments and (ii) sequencing genotypes from multiple locations and characterizing geographic patterns in allele frequency. Both approaches aim to characterize the same pattern (local adaptation), yet the complementary information from each has not yet been coherently integrated. Here, we develop a genome‐wide association model of genotype interactions with continuous environmental gradients (G × E), that is reaction norms. We present an approach to impute relative fitness, allowing us to coherently synthesize evidence from common garden and genome–environment associations. Our approach identifies loci exhibiting environmental clines where alleles are associated with higher fitness in home environments. Simulations show our approach can increase power to detect loci causing local adaptation. In a case study on Arabidopsis thaliana, most identified SNPs exhibited home allele advantage and fitness trade‐offs along climate gradients, suggesting selective gradients can maintain allelic clines. SNPs exhibiting G × E associations with fitness were enriched in genic regions, putative partial selective sweeps and associations with an adaptive phenotype (flowering time plasticity). We discuss extensions for situations where only adaptive phenotypes other than fitness are available. Many types of data may point towards the loci underlying G × E and local adaptation; coherent models of diverse data provide a principled basis for synthesis.     

Mixed species nesting associations in Darwin's tree finches: nesting pattern predicts predation outcome

Predation is the main cause of passerine nesting failure. Traditionally, large intraspecific group size is thought to accrue individuals with fitness benefits from increased predator vigilance and hence lower predation risk. To date, few studies have investigated interspecific group size in relation to predation risk. In the present study, we examined predation outcome in Darwin's small tree finch, Camarhynchus parvulus , in nests with many or few interspecific neighbours. We tested the predictions: (1) nests in mixed associations have lower predation than do more solitary nests; (2) mixed species nesting associations covary with nest site vegetation characteristics; (3) older (i.e. presumably experienced) males more commonly nest in mixed associations than younger males; (4) older males select more concealed nesting sites; and (5) controlling male age, females prefer to pair with males in mixed associations than at solitary nests. Almost half of all nests occurred in mixed associations (46%) compared to solitary nests (54%), and the overall distribution of nests was decidedly nonrandom, displaying a bimodal pattern. Nest site vegetation characteristics of the focal species were inconsistently associated with nesting pattern, but older males did select more concealed nesting sites. Controlling differences in surrounding vegetation characteristics, mixed nesting associations experienced markedly lower predation than solitary nests, and females showed a preference for males in mixed associations, as demonstrated by higher male pairing success.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 313–324.     

Presence of other species may counter seasonal decline in breeding success: a field experiment with pied flycatchers Ficedula hypoleuca

Seasonal decline in breeding success limits fitness in many bird species nesting in the temperate, boreal and arctic zones. Factors affecting this decline, especially if the decline is reduced, can thus have significant ecological and evolutionary importance. In an experiment designed to investigate fitness consequences of heterospecific attraction, no seasonal decline in breeding success was observed for pied flycatchers Ficedula hypoleuca breeding in the presence of resident titmice Parus spp., whereas a pattern of steep decline was observed for birds breeding in areas where residents were removed. Randomisation of removal treatment and pied flycatcher territories with respect to arrival date leaves enhanced foraging that results from the presence of resident titmice during breeding as the best, albeit currently hypothetical, explanation for the observed absence of a seasonal decline. Among terrestrial vertebrates, reports of this kind of direct positive interactions are rare.     

LIFE-CYCLE COMPONENTS OF SELECTION IN ERIGERON ANNUUS: II. GENETIC VARIATION

Genetic variation for seedling and adult fitness components was measured under natural conditions to determine the relative importance of the seedling stage for lifetime fitness in Erigeron annuus. Variation in lifetime reproductive success can result from both the persistent effects of genetic variation expressed among seedlings and from variation in adult fitness components. Analysis of covariance was used to separate the stage specific from the cumulative effects of genetic variance expressed earlier in the life cycle. E. annuus produces seeds through apomixis, which allowed measurement of the fitness of replicate genotypes from germination through the entire life cycle. There were significant differences among genotypes for date of emergence, seedling size, survivorship and fecundity, but heritabilities were low, indicating slow response to selection. For all characters, environmental components of variance were one to two orders of magnitude larger than genetic variance components, resulting in broad sense heritabilities less than 0.1. For seedling size and fecundity, all of the genetic variance was in the form of genotype-environment interactions, often with large negative genetic correlations across environments. In contrast, genotypes differed in mean survivorship through one year, but there were no genotype-environment interactions for viability. Genetic differences in viability were primarily expressed as differences in overwinter survivorship. Genotype × environment interactions among sites and blocks were generated early in the life cycle while the genotype × environment interactions in response to competitive environment (open, annual cover, perennial cover) first appeared in adult fecundity. Genetic variation in lifetime fitness was not significant, despite a fourfold difference in mean fitness among genotypes.     

Influence of immune‐relevant genotype on the reproductive success of a salmonid alternative mating strategy

Major histocompatibility complex (MHC) and immune‐relevant gene markers were used to evaluate differences in reproductive success (RS) among naturally spawning coho salmon Oncorhynchus kisutch mate pairs involving an alternative male reproductive phenotype, known as jacks. These mate pairs included both hatchery‐reared and wild origin fish such that three classes were evaluated in two consecutive years (2005 and 2006) using a previously constructed multigenerational genetic pedigree: wild × wild (W × W), hatchery × hatchery (H × H) and wild × hatchery (W × H). Oncorhynchus kisutch jack mate pairs mated randomly based on immune‐relevant genotype in both years; a result consistent with the opportunistic mating strategy of jacks. An association between greater number of alleles shared at three immune‐relevant gene markers and increased RS was found for: W × H mate pairs in 2005 (BHMS429), W × H pairs in 2006 (SsalR016TKU) and W × W pairs in 2006 (OMM3085). No correlation between immune gene diversity and RS was found for H × H pairs in either year. The results suggest that the influence of immune‐relevant genotype on mating success may be different for jacks when compared with previous studies of large adult male O. kisutch.     

Breeding density,habitat selection and reproductive rates of the Peregrine Falcon Falco peregrinus in Álava (northern Spain)

A population of 33–35 pairs of Peregrine Falcon in álava (north Spain) was studied with the aim of assessing the habitat attributes that influence breeding density, habitat selection and breeding success. A strong relationship was found between density of the species in each UTM (Universal Transverse Mercator) square of 10 × 10 km and cliff availability. Habitat selection was analysed by comparing 15 variables in 33 occupied and 25 unoccupied cliffs located at least 2 km from the nearest Peregrine pair. Significant differences were found in five variables: cliff dominance, distance to the nearest Golden Eagle Aquila chrysaetos nesting cliff, steepness and altitude (all showing larger values in occupied cliffs), and cliff orientation, with occupied cliffs facing preferably south and east. Orientation, dominance and distance to the nearest Golden Eagle pair, and the distance to the nearest Eagle Owl Bubo bubo nesting cliff, were included in a discriminant analysis which classified 82.76% of the cliffs correctly. The productivity of the studied population was 1.44 young/territorial pair (n = 45), and no consistent relationship was found between breeding success and habitat variables.     

Nests in the cities: adaptive and non-adaptive phenotypic plasticity and convergence in an urban bird

Phenotypic plasticity plays a critical role in adaptation to novel environments. Behavioural plasticity enables more rapid responses to unfamiliar conditions than evolution by natural selection. Urban ecosystems are one such novel environment in which behavioural plasticity has been documented. However, whether such plasticity is adaptive, and if plasticity is convergent among urban populations, is poorly understood. We studied the nesting biology of an ‘urban-adapter’ species, the dark-eyed junco (Junco hyemalis), to understand the role of plasticity in adapting to city life. We examined (i) whether novel nesting behaviours are adaptive, (ii) whether pairs modify nest characteristics in response to prior outcomes, and (iii) whether two urban populations exhibit similar nesting behaviour. We monitored 170 junco nests in urban Los Angeles and compared our results with prior research on 579 nests from urban San Diego. We found that nests placed in ecologically novel locations (off-ground and on artificial surfaces) increased fitness, and that pairs practiced informed re-nesting in site selection. The Los Angeles population more frequently nested off-ground than the San Diego population and exhibited a higher success rate. Our findings suggest that plasticity facilitates adaptation to urban environments, and that the drivers behind novel nesting behaviours are complex and multifaceted.     

Comparative breeding ecology of Mississippi Kites in urban and exurban areas of West Texas

Birds of prey are becoming increasingly common occupants of urbanized settings, but the comparative benefits or detriments they experience in urban environs compared to exurban areas are poorly understood. We examined the reproductive success and phenology of Mississippi Kites (Ictinia mississippiensis) nesting concurrently in urban and exurban areas in west Texas during the 2010–2012 and 2014 breeding seasons. Our objective was to better understand the reproductive advantages or disadvantages that kites may experience by nesting in urban areas rather than exurban areas. We calculated annual productivity, estimated daily survival rates of nests, and estimated hatch dates. Kites produced 0.52 fledglings per urban nesting attempt and 0.33 fledglings per exurban nesting attempt. We found no difference in the mean number of young that fledged from successful urban (1.06) and exurban (1.07) nests, but kites in urban areas had greater nesting success within years than those in exurban areas. Both heat and drought were associated with low productivity and success in both areas, but the urban landscape appears to have provided some buffer to their effects. These factors may have had direct (e.g., exposure) or indirect (e.g., negative influences on prey availability) influences on reproductive success. Counter to previous studies of urban raptors, we found that exurban kites nested significantly earlier than urban kites. This may be linked to differences in environmental conditions and prey availability between the areas. Our results suggest that urban areas provide a reproductive advantage for Mississippi Kites in terms of facilitating an overall higher nesting success, but this does not translate into increased productivity for successful pairs. Further, our data suggest that, although urban areas may buffer species from drought or heat, that buffer can be breached during severe conditions.     

Waterfowl Use of Dense Nesting Cover in the Canadian Parklands

ABSTRACT Dense nesting cover (DNC) has been a conspicuous component of habitat management for upland-nesting ducks for >30 years, but its benefits for nesting ducks have been contentious. During 1994–1999 we monitored 3,058 dabbling duck (Anas spp.) nests in 84 DNC fields located throughout the Canadian Parklands to examine sources of among-field variation in nest density and nesting success. Nest density averaged 1.51 (SE=0.15) nests/ha and overall nesting success was 20.4%, but there was pronounced annual variation in both estimates. Nesting success increased with increasing field size (range = 6–111 ha), but nest density remained constant. Nest density increased with percent wetland habitat within DNC fields and declined with percent perennial cover in the surrounding 2.4 × 2.4-km landscape, but these variables were not important for predicting nesting success. Nest abundance and nesting success roughly doubled in fields seeded with alfalfa (Medicago sativa) or sweet clovers (Melilotus spp.), but there was no benefit from using native as opposed to tame grasses. We recommend that waterfowl managers in the Canadian Parklands establish DNC with alfalfa in large fields in landscapes with abundant wetlands but minimal competing cover.