Effects of forest canopy on habitat selection in treefrogs and aquatic insects: implications for communities and metacommunities

The specific dispersal/colonization strategies used by species to locate and colonize habitat patches can strongly influence both community and metacommunity structure. Habitat selection theory predicts nonrandom dispersal to and colonization of habitat patches based on their quality. We tested whether habitat selection was capable of generating patterns of diversity and abundance across a transition of canopy coverage (open and closed canopy) and nutrient addition by investigating oviposition site choice in two treefrog species (Hyla) and an aquatic beetle (Tropisternus lateralis), and the colonization dynamics of a diverse assemblage of aquatic insects (primarily beetles). Canopy cover produced dramatic patterns of presence/absence, abundance, and species richness, as open canopy ponds received 99.5% of propagules and 94.6% of adult insect colonists. Nutrient addition affected only Tropisternus oviposition, as females oviposited more egg cases at higher nutrient levels, but only in open canopy ponds. The behavioral partitioning of aquatic landscapes into suitable and unsuitable habitats via habitat selection behavior fundamentally alters how communities within larger ecological landscapes (metacommunities) are linked by dispersal and colonization.     

Effects of flash flooding on mosquito and community dynamics in experimental pools

Pulsed disturbances of larval mosquito sites are likely to have a direct negative effect on mosquitoes but may also have indirect effects due to the alteration of community structure. These altered communities may become attractive to gravid mosquitoes searching for oviposition sites when the disturbances decrease the abundance of mosquito antagonists such as competitors, which often results in an increase in mosquito food resources. However, flash flood disturbances in intermittent riverbeds can also remove mosquito food resources such as algae, so that the net effect of flash floods could be either to increase or decrease mosquito abundance. We conducted an outdoor mesocosm experiment to assess the effects of flash floods on mosquito oviposition habitat selection and larval abundance during the post‐disturbance period of community recovery. Mesocosms were artificially flooded. Mosquito oviposition, immature abundance, invertebrate species diversity, chlorophyll a, and abiotic parameters were monitored. Our results showed that the flash flood negatively affected phytoplankton and zooplankton, leading to a decrease of mosquito oviposition in flooded mesocosms compared to non‐flooded mesocosms. More broadly, this study indicates how disturbances influence mosquito oviposition habitat selection due to the loss of food resources in ephemeral pools, and it highlights the importance of considering the effects of disturbances in management, habitat restoration, and biodiversity conservation in temporary aquatic habitats.     

Habitat quality favoured over familiarity: a rejection of natal habitat preference induction in the mosquito Aedes albopictus

1. Natal habitat preference induction (NHPI) is a behavioural phenomenon in which offspring show a change in preference in adult oviposition choice as a function of experience as an immature. 2. Although well known in certain systems, such as herbivorous insects, this behaviour has not been well studied in aquatic insects. 3. The container–breeding mosquito, Aedes albopictus (Skuse) was used to test if NHPI occurs in aquatic insects under natural conditions of two leaf species as a nutritive base (Juniperus virginiana L. and Quercus virginiana Mill) and two larval densities. 4. Significant effects of leaf species and density on adult mosquito attributes were found, with J. virginiana and low larval density associated with more, faster developing, larger and more fecund mosquitoes. However, no evidence for NHPI was found. Instead a canalised behavior was found that included spreading eggs between high– and low–quality oviposition choices in the same proportions regardless of larval experience.     

The effect of vegetation patterns on oviposition habitat preference: A driving mechanism in terrestrial chironomid (Diptera: Chironomidae) succession?

Relationships between changes of two species of terrestrial chironomids(Smittia cf. aterrima andBryophaenocladius cf. virgo) and changes of vegetation cover during succession were studied with respect to plant — chironomid interaction in particular stages of chironomid life cycle. Several vegetation types forming vegetation mosaics in suburban fallow were distinguished according to their spatial architecture (height; density etc.). Abundance of chironomid larvae in particular type of vegetation and an area covered by these vegetation types were studied for three years. During one year the effect of vegetation types on density of aerial drift, oviposition habitat preference and adult emergence was studied in detail. Aerial drift was studied using pan traps, oviposition using soil sampling and adult emergence using emergence trap. Main results were similar for both species. Chironomid larvae were abundant in soil in initial years of succession. They were concentrated in patches with open and low height vegetation. Later their abundance decreased corresponding to a reduction of open and low vegetation areas. Greater density of aerial drift and oviposition preference was observed in areas of open and low vegetation. The success of larval development agreed with oviposition preference for winter larval generation only. The less preferred habitats seemed to be more suitable for summer generation. The results indicated that successional changes of terrestrial chironomids can be explained by the effect of vegetation cover on oviposition habitat preference.     

Efficacy of aquatain, a monomolecular film, for the control of malaria vectors in rice paddies

Background

Rice paddies harbour a large variety of organisms including larvae of malaria mosquitoes. These paddies are challenging for mosquito control because their large size, slurry and vegetation make it difficult to effectively apply a control agent. Aquatain, a monomolecular surface film, can be considered a suitable mosquito control agent for such breeding habitats due to its physical properties. The properties allow Aquatain to self-spread over a water surface and affect multiple stages of the mosquito life cycle.

Methodology/Principal Findings

A trial based on a pre-test/post-test control group design evaluated the potential of Aquatain as a mosquito control agent at Ahero rice irrigation scheme in Kenya. After Aquatain application at a dose of 2 ml/m² on rice paddies, early stage anopheline larvae were reduced by 36%, and late stage anopheline larvae by 16%. However, even at a lower dose of 1 ml/m² there was a 93.2% reduction in emergence of anopheline adults and 69.5% reduction in emergence of culicine adults. No pupation was observed in treated buckets that were part of a field bio-assay carried out parallel to the trial. Aquatain application saved nearly 1.7 L of water in six days from a water surface of 0.2 m² under field conditions. Aquatain had no negative effect on rice plants as well as on a variety of non-target organisms, except backswimmers.

Conclusions/Significance

We demonstrated that Aquatain is an effective agent for the control of anopheline and culicine mosquitoes in irrigated rice paddies. The agent reduced densities of aquatic larval stages and, more importantly, strongly impacted the emergence of adult mosquitoes. Aquatain also reduced water loss due to evaporation. No negative impacts were found on either abundance of non-target organisms, or growth and development of rice plants. Aquatain, therefore, appears a suitable mosquito control tool for use in rice agro-ecosystems.     

Plant stem density as a cue in patch choice by foraging juvenile bluegill sunfish

Synopsis Juvenile bluegill sunfish,Lepomis macrochira, are restricted to vegetated habitats by predators. Variation in plant stem density has a significant effect on bluegill foraging success. Given the mosaic nature of this habitat, plant stem density may provide a cue for selecting among patches in which to forage. In this study, juvenile bluegills were offered patches of artificial vegetation differing only in plant stem density as potential foraging sites. Three densities, 100, 250, and 500 stems m^–2 were tested. Fish were presented with a choice between patches (100:250, 250:500, or 100:500). Bluegill foraging rate in, and the number of fish choosing each patch was recorded. Juvenile bluegills showed a preference for those patches which maximized their foraging rate.     

Wetland isolation facilitates larval mosquito density through the reduction of predators

• 1 Wetlands harbour high biodiversity and offer important ecosystem services, but they are also a habitat for mosquito larvae (Diptera: Culicidae), which are important disease vectors.
• 2 Isolation among remnant, or newly created wetlands and ponds, and their consequent density in the landscape, is a key factor that can influence a variety of food web processes, including effects on mosquitoes which are important prey to many predators.
• 3 We assess the impact of habitat isolation on the density of pond‐breeding mosquitoes (several Anopheles and Culex species) both directly and indirectly through the food web.
• 4 Results from structural equation modelling of survey data shows that larval mosquitoes are denser in ponds that are more isolated from one another, and that this result was primarily driven indirectly by a reduction of larval mosquito predators (e.g. predaceous insects and amphibians). Furthermore, results from a long‐term mesocosm experiment factorially manipulating isolation and predator reduction show that the effect of isolation on mosquito density was eliminated when predators were experimentally reduced.
• 5 It is concluded that metacommunity processes, both directly and indirectly mediated through predators, can play an important role in the local abundance of wetland breeding mosquitoes and possibly the diseases they spread.

     

Physical,Chemical and Biological Characteristics in Habitats of High and Low Presence of Anopheline Larvae in Western Kenya Highlands

Background

Characteristics of aquatic habitats determine whether mosquitoes will oviposit, hatch, develop, pupate and successfully emerge into adults or not, thus influencing which mosquito species will occupy a habitat. This study determined whether physiochemical and biological characteristics differ between habitats with high and low presence of anopheline larvae.

Methods

Physical, chemical and biological characteristics were evaluated in selected habitats twice per month within three highland valleys in western Kenya. Aquatic macro-organisms were sampled using a sweep-net. Colorimetric methods were used to determine levels of iron, phosphate, nitrate, ammonium and nitrite in water samples. Generalized Estimating Equations (GEE) was used to compare parameters between the two categories of anopheline presence.

Results

Habitats with high anopheline presence had greater abundance of mosquito aquatic stages and tadpoles and two times more levels of nitrate in water, whereas habitats with low anopheline presence had wider biofilm cover and higher levels of iron in water.

Conclusion

Habitats of high and low presence of anopheline larvae, which differed in a number of physical, chemical and biological characteristics, were identified in valleys within western Kenya highlands. Differences in habitat characteristics are critical in determining the number of anopheline larvae that will fully develop and emerge into adults.     

Population structure of stream-dwelling darters: correspondence with habitat structure

Synopsis Patterns of ecotopic variation in the population structure of two common and relatedPercina species were examined among seven central Gulf-Coast stream sites by Kendall's concordance tests, revealing four complexes of variables with significant covariation from a total of 18 population and habitat variables. The first complex comprised three interrelated habitat variables, implying that mid-stream surface current varied inversely with both instream cover and substrate heterogeneity. The second complex of five interrelated variables revealed (1) that darter abundance was better correlated with the area of instream cover than with total area, and (2) that site density [number m^-2] varied inversely with site area. Along with three other variables, cover density (number per square meter of instream cover) formed a third complex, demonstrating resource complementarity between instream cover and macroinvertebrate abundance. Variables within the fourth complex all increased concomitantly with the key variable of mean darter size, including body-size diversity, biomass, relative abundance of the two darter species and mid-stream depth. Within the study region, local ecological factors largely regulate distributions, abundances and size-structures ofPercina populations, apparently even outweighing the effects of stochastic and historical factors     

Diversity of anopheline mosquitoes (Diptera: Culicidae) and classification based on the characteristics of the habitats where they were collected in Puerto Iguazú, Misiones,Argentina

In order to extend the knowledge of anopheline diversity and their habitats in three environments with different degrees of anthropic intervention in Puerto Iguazú, Misiones, anopheline larvae were collected and classified on the basis of similarities of their habitats. Spatio‐temporal abundance was determined and larval diversity and complementarity index were calculated. Rank‐abundance curves were performed to compare the composition, abundance, and species evenness among environments. A total of 783 larvae, belonging to six species: Anopheles argyritarsis, An. fluminensis, An. mediopunctatus, An. punctimacula, An. strodei s.l., and An. triannulatus s.l., were collected. A cluster analysis and a principal component analysis detected two groups; exposure to sunlight and type of habitat were the characteristics that explained the grouping of species. Higher abundances of anopheline larvae were observed during autumn and spring. The greatest richness was recorded in wild and peri‐urban environments and the effective number of species was greater in the wild. Anopheles punctimacula and An. triannulatus s.l. are secondary vectors of malaria in other South American countries and both species were found in the three environments, so that deforestation poses a potential risk for malaria transmission as it contributes to the proliferation of larval habitats for these mosquitoes.     

Bioinsecticide and leaf litter combination increases oviposition and reduces adult recruitment to create an effective ovitrap for Culex mosquitoes

Mosquito egg traps, aquatic habitats baited with oviposition attractant and insecticide, are important tools for surveillance and control efforts in integrated vector management programs. The bioinsecticide Bacillus thuringiensis subsp. israelensis (Bti) is increasingly used as an environmentally friendly alternative to chemical insecticides and the combination of Bti with a simple oviposition attractant like leaf litter to create an effective egg trap seems appealing. However, previous research suggests that Bti may itself alter oviposition, and that leaf litter may dramatically reduce Bti toxicity. Here we present results from field experiment designed to link the effects of litter and Bti on mosquito oviposition habitat selection and post‐colonization survival to production of adult mosquitoes. Tripling litter increased Culex spp. oviposition nearly nine‐fold, while Bti had no effect on oviposition. Neither factor altered egg survival, thus larval abundance reflected the effects of litter on oviposition. Both Bti and litter reduced larval survival by ～60%. We found no evidence that increased litter reduced Bti toxicity. Adult production was dependent upon both litter and Bti. In the absence of Bti, effects of litter on oviposition translated into three‐fold more adults. However, in the presence of Bti, initial increases in oviposition were erased by the combined negative effects of Bti and litter on post‐colonization survival. Thus, our study provides field evidence that combined litter and Bti application creates an effective ovitrap. This combined treatment had the highest oviposition and the lowest survival, and thus removed the greatest number of mosquitoes from the landscape.     

Experimental formulations ofBacillus sphaericus for the control of anopheline and culicine larvae

Summary Four experimental formulations ofBacillus sphaericus Neide (2362 isolate) were evaluated for larvicidal activity against culicine and anopheline larvae in several natural and artificial habitats. A granular formulation (5% primary powder) was tested against natural populations of mosquitoes in two simulated habitats in Florida and in maturing and reflooded rice fields in Louisiana. Larvae ofCulex quinquefasciatus Say were reduced by 97 and 99% after application of the granules at the rate of 10 kg/ha to polluted tanks and 2.5 kg/ha to sod-lined potholes, respectively. Anopheline andPsorophora columbiae (Dyar and Knab) larvae were reduced by 68 and 92–100%, respectively, after application of 5 kg granules/ha to rice fields. A flowable concentrate (12.8% primary powder) applied to unpolluted and organically enriched habitats in Florida at 0.25 kg/ha reduced populations ofCulex spp. by 93–100% and 99%, respectively. Sustained-release briquets (5% primary powder) applied at the rate of one half briquet/1.8 m² sod-lined potholes reduced larval populations ofCx. quinquefasciatus by 88–95% for up to 2 weeks in open sunlight. Sustained-release pellets (30% primary powder) applied to small woodland pools in Memphis, TN at the rate of four pellets/pool virtually eliminated larval populations ofCx. restuans Theobald for over 8 days. Variable persistance of larvicidal activity was noted for the other treatments depending on the formulation, target species and habitat.     

Yeast communities of the cactusPilosocereus arrabidae as resources for larval and adult stages ofDrosophila serido

The feeding behavior ofDrosophila serido on the yeast communities of necrotic stem tissue ofPilosocereus arrabidae were studied in a sand dune ecosystem of Rio de Janeiro, Brazil. The prevalence of cactophilic yeasts includingPichia barkeri, Candida sonorensis andGeotrichum sp. in the crops and external surfaces ofD. serido reflected its association with the cactus habitat. The effective number of yeasts vectored on the surface of flies was higher than that in the crops. Also overlap between the yeasts from stems and from crops was partial suggesting selective feeding by the flies in the substrates visited. The females had a higher effective number of yeast species and a lower similarity than males with the yeast community ofP. arrabidae. This was probably related to the search for oviposition sites by females. The presence ofPichia thermotolerans-like andPichia amethionina varpachycereana in the flies, but not inP. arrabidae stems, indicated thatD. serido was not limited to this cactus species. The larvae and adults lived in different patches with the adults feeding in patches with higher yeast species richness. The larvae had a narrower feeding niche and higher overlap withP. arrabidae, and preferredP. barkeri andPichia cactophila as food. Adult flies fed on patches with the most frequent yeasts except forP. cactophila. Pichia caribaea was found in higher frequency in the adult crops than in the stems. Our data suggested that there was food selection and diet partitioning between adult and larval stages ofD. serido.     

Maternal behaviours may explain riffle‐scale variations in some stream insect populations

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Anopheline Larval Habitats Seasonality and Species Distribution: A Prerequisite for Effective Targeted Larval Habitats Control Programmes

Background

Larval control is of paramount importance in the reduction of malaria vector abundance and subsequent disease transmission reduction. Understanding larval habitat succession and its ecology in different land use managements and cropping systems can give an insight for effective larval source management practices. This study investigated larval habitat succession and ecological parameters which influence larval abundance in malaria epidemic prone areas of western Kenya.

Methods and Findings

A total of 51 aquatic habitats positive for anopheline larvae were surveyed and visited once a week for a period of 85 weeks in succession. Habitats were selected and identified. Mosquito larval species, physico-chemical parameters, habitat size, grass cover, crop cycle and distance to nearest house were recorded. Polymerase chain reaction revealed that An. gambiae s.l was the most dominant vector species comprised of An.gambiae s.s (77.60%) and An.arabiensis (18.34%), the remaining 4.06% had no amplification by polymerase chain reaction. Physico-chemical parameters and habitat size significantly influenced abundance of An. gambiae s.s (P = 0.024) and An. arabiensis (P = 0.002) larvae. Further, larval species abundance was influenced by crop cycle (P≤0.001), grass cover (P≤0.001), while distance to nearest houses significantly influenced the abundance of mosquito species larvae (r = 0.920;P≤0.001). The number of predator species influenced mosquito larval abundance in different habitat types. Crop weeding significantly influenced with the abundance of An.gambiae s.l (P≤0.001) when preceded with fertilizer application. Significantly higher anopheline larval abundance was recorded in habitats in pasture compared to farmland (P = 0.002). When habitat stability and habitat types were considered, hoof print were the most productive followed by disused goldmines.

Conclusion

These findings suggest that implementation of effective larval control programme should be targeted with larval habitats succession information when larval habitats are fewer and manageable. Crop cycles and distance from habitats to household should be considered as effective information in planning larval control.     

Effects of the removal or reduction in density of the malaria mosquito,Anopheles gambiae s.l., on interacting predators and competitors in local ecosystems

New genetic control methods for mosquitoes may reduce vector species without direct effects on other species or the physical environment common with insecticides or drainage. Effects on predators and competitors could, however, be a concern as Anopheles gambiae s.l. is preyed upon in all life stages. We overview the literature and assess the strength of the ecological interactions identified. Most predators identified consume many other insect species and there is no evidence that any species preys exclusively on any anopheline mosquito. There is one predatory species with a specialisation on blood‐fed mosquitoes including An. gambiae s.l.. Evarcha culicivora is a jumping spider, known as the vampire spider, found around Lake Victoria. There is no evidence that these salticids require Anopheles mosquitoes and will readily consume blood‐fed Culex. Interspecific competition studies focus on other mosquitoes of larval habitats. Many of these take place in artificial cosms and give contrasting results to semi‐field studies. This may limit their extrapolation regarding the potential impact of reduced An. gambiae numbers. Previous mosquito control interventions are informative and identify competitive release and niche opportunism; so while the identity and relative abundance of the species present may change, the biomass available to predators may not.     

Effect of desiccation on mosquito oviposition site selection in Mediterranean temporary habitats

1. Hydroperiod duration has been identified as the main factor determining the faunal composition and structure of aquatic communities in temporary habitats. It is hypothesised that desiccation will positively affect mosquito oviposition habitat selection during the post-drought period due to the lack of antagonists. 2. An experiment was carried out in outdoor mesocosms to assess whether desiccation events have post-drought effects on community richness and mosquito oviposition. Three different treatments were randomly assigned to the mesocosms: (i) eight mesocosms were left dried for a week and then reflooded; (ii) eight mesocosms stayed dry for 4 weeks before they were reflooded; (iii) eight mesocosms were maintained at a constant water volume of 30 litres during the entire experiment as controls. Mosquito oviposition and invertebrate community richness were monitored in every mesocosm, along with environmental parameters [water temperature, pH, conductivity, dissolved oxygen, total suspended solids (TSS) and chlorophyll a concentration]. 3. Post-drought mosquito oviposition and larval abundance were higher in the short-drought and long-drought pools than in the control. Desiccation negatively affected the biomass of the filter feeder invertebrates in both desiccation treatments. Chlorophyll a concentrations were higher in the long-drought pools than in controls. The negative impact of desiccation on zooplankton led to a post-drought increase in algae, associated with an increase in mosquito oviposition. 4. Despite immediate negative effect on mosquitoes, pulsed disturbances can benefit mosquitoes as they favour oviposition during the post-disturbance recovery period due to a lower abundance of mosquito antagonists and higher food resources for their offspring.     

Invasive reed effects on benthic community structure in Lake Erie coastal marshes

We examined how dominance (% canopy cover) and invasion history of common reed, Phragmites australis, affected benthic macroinvertebrate diversity and density in 8 marshes along Lake Erie’s southern shoreline. We also compared macroinvertebrate densities among patches (0.25 m²) of reed, cattail (Typha spp.), and native flora (e.g., Sagittaria, Sparganium) and epiphytic algal communities on submerged stems of reed and cattail. Narrow-leaf cattail (T. angustifolia) is also a common invasive plant to these wetlands, but does not greatly change plant community composition or ecosystem conditions like reed. Macroinvertebrate diversity (Shannon–Weaver H′) was positively related to reed cover and was highest (4.6) in two marshes with ~35- and 5-year invasion histories. Shading from high reed cover increased H′-diversity, in part, by reducing the abundance of floating duckweed, which harbored many Hyalella azteca amphipods. Percent Ephemeroptera, Odonata, and Trichoptera was low to moderate across marshes, regardless of reed cover and invasion history. Macroinvertebrate density was not affected by reed cover or average plant stem density, and did not differ among plant types. However, epiphyton densities and % diatoms were greater on reed than on cattail, suggesting reed provides a better feeding habitat for microalgal grazers than Typha. Abundance rankings of common species in these diatom-dominated communities were also typically dissimilar between these plant types. Although % grazers was unrelated to epiphyton densities and % diatoms, grazer identity (snails) differed between natural and diked marshes, which had different microalgal food supplies. Our findings suggest that Phragmites does not necessarily adversely affect macroinvertebrate community structure and diversity and that invasion history alone has little effect on the H′-diversity–reed dominance relationship.     

Effect of vegetation density, height, and connectivity on the oviposition pattern of the leaf beetle Galeruca tanaceti

Vegetation structure can profoundly influence patterns of abundance, distribution, and reproduction of herbivorous insects and their susceptibility to natural enemies. The three main structural traits of herbaceous vegetation are density, height, and connectivity. This study determined the herbivore response to each of these three parameters by analysing oviposition patterns in the field and studying the underlying mechanisms in laboratory bioassays. The generalist leaf beetle, Galeruca tanaceti L. (Coleoptera: Chrysomelidae), preferentially deposits its egg clutches on non‐host plants such as grasses. Earlier studies revealed that oviposition within structurally complex vegetation reduces the risk of egg parasitism. Consequently, leaf beetle females should prefer patches with dense, tall, or connected vegetation for oviposition in order to increase their reproductive success. In the present study, we tested the following three hypotheses on the effect of stem density, height, and connectivity on oviposition: (1) Within habitats, the number of egg clutches in areas with high stem densities is disproportionately higher than in low‐density areas. The number of egg clutches on (2) tall stems or (3) in vegetation with high connectivity is higher than expected for a random distribution. In the field, stem density and height were positively correlated with egg clutch presence. Moreover, a disproportionately high presence of egg clutches was determined in patches with high stem densities. Stem height had a positive influence on oviposition, also in a laboratory two‐choice bioassay, whereas stem density and connectivity did not affect oviposition preferences in the laboratory. Therefore, stem height and, potentially, density, but not connectivity, seem to trigger oviposition site selection of the herbivore. This study made evident that certain, but not all traits of the vegetation structure can impose a strong influence on oviposition patterns of herbivorous insects. The results were finally compared with data on the movement patterns of the specialised egg parasitoid of the herbivore in comparable types of vegetation structure.     

Influence of Juniper on Montezuma Quail Habitat Use in Texas

Montezuma quail (Cyrtonyx montezumae) inhabit oak (Quercus spp.)-juniper (Juniperus spp.) woodlands throughout Mexico and the southwestern United States. In Texas, USA, Montezuma quail occur in the Edwards Plateau and Trans-Pecos Mountains and Basins (Trans-Pecos), 2 ecoregions with contrasting juniper patterns. Ashe juniper (Juniperus ashei) dominates in the Edwards Plateau and has been increasing over decades, whereas alligator juniper (Juniperus deppeana) is a co-dominant in the Trans-Pecos and appears to have stable Montezuma quail populations. Our objectives were to compare between ecoregions the relative abundance and habitat use of Montezuma quail in relation to juniper and quantify the influence of juniper on key features of Montezuma quail habitat (grass height, grass cover, forb cover, and forb species richness). We conducted a study from March–August 2018‒2020 in the Edwards Plateau (Kinney and Edwards counties) and Trans-Pecos ecoregions (Jeff Davis County) to evaluate these objectives. We conducted call-back surveys to estimate relative abundance (number of detections/hr) of Montezuma quail and identify used locations. We collected vegetation data at a micro-scale (16-m) at used (n = 32–30 points) and random locations (n = 70–60 points) in each ecoregion. Relative abundance of Montezuma quail was considerably lower in the Edwards Plateau (0.06 ± 0.01 detections/survey hr; ± SE) than in the Trans-Pecos (1.10 ± 0.30 detections/survey hr). In addition, Montezuma quail selected areas of low Ashe juniper cover (<23% cover), density (<7 trees/80 m²), and height (<2 m) in the Edwards Plateau but selected areas of high alligator juniper cover (>18% cover), density (>4 trees/80 m²), and height (2–8 m) in the Trans-Pecos. Moreover, Ashe juniper cover had a significant, negative influence on herbaceous features, whereas alligator juniper exerted little to no influence. Our results suggest that these 2 juniper species have contrasting effects on Montezuma quail space use and their habitat, possibly as a result of the contrasting influence of these junipers on herbaceous understory. Creating habitat for Montezuma quail in the Edwards Plateau generally will involve the reduction of Ashe juniper and creating patches that possess juniper trees of small stature (<2 m) with low amounts of cover (<23%) and density (<7 trees/80 m²), whereas management in the Trans-Pecos will require site-specific assessments based on current alligator juniper influence. © 2021 The Wildlife Society.