Small Fish Ponds Research Articles

Lernaea cf. cyprinacea infection in agile frog (Rana dalmatina) tadpoles in Hungary.

The ectoparasitic copepod Lernaea cyprinacea (anchor worm) has more than 100 host species among teleost fishes and affects cyprinids both in fish farms and natural waters. In addition, while L. cyprinacea infection in amphibians has been recorded in Asia, North and South America, there is no data available in the literature on their presence in Europe. In this study, we first reported L. cf. cyprinacea parasitising an anuran tadpole in Europe. Specimens of L. cf. cyprinacea were observed attached to a tadpole of the agile frog (Rana dalmatina), which was caught during fishing of crucian carp fingerlings (Carassius carassius) from a small fish pond in Hungary during the summer of 2012. The infected tadpole was collected from a rearing pond, where juvenile crucian carps were kept. The tadpole was inspected in the laboratory, and digital photos were taken. The parasites were found attached to the body-tail junction and to the leg of the tadpole (at Gosner stage 41). The parasite species was identified as L. cf. cyprinacea based on morphological traits.

Phytoplankton-zooplankton coupling in a cascade of hypertrophic fishponds

In Central Europe, a significant proportion of shallow lake ecosystems are represented by artificial fishponds, where phytoplankton and zooplankton are an essential part of the food web. Owing to their high fish stocks and intensive fishery management, most fishponds are now eutrophic or hypertrophic, which has had clear impacts on plankton assemblages. To obtain a better understanding of phytoplankton-zooplankton coupling in fishponds, this study examines their ecological relationships in a cascade of three small fishponds over two subsequent years. In all, 133 phytoplankton taxa were recorded, mostly chlorophytes, diatoms and euglenophytes, and 60 zooplankton taxa. Multivariate analysis revealed dissolved oxygen content, dissolved inorganic nitrogen and biochemical oxygen demand as the main factors influencing phytoplankton biomass, while the most significant environment variables affecting zooplankton composition were dissolved oxygen, phosphate concentrations and conductivity. Co-correspondence analysis revealed a significant relationship between phytoplankton and zooplankton density, with cross-correlations from 76% to 87% within the first four axes. Such a high cross-correlation denotes a strong relationship between phytoplankton and zooplankton, even within the hypertrophic conditions determining fishpond ecosystems.

Differences in the plankton communities of newly-created small fishponds under different fishery management regimes

Differences in the plankton communities of newly-created small fishponds under different fishery management regimes

Isotopic kinetic fractionation of evaporation from small water bodies

The primary objective of this study is to investigate the kinetic fractionation of evaporation of small water bodies. The experiments were performed in outdoor conditions using two evaporation pans and a small fishpond. The work is motivated in part by the high sensitivity of lake evaporation derived from isotopic mass balance to the strength of the kinetic effect. Results show that the kinetic factor εk for the oxygen isotopes is inversely related to the water-to-air temperature gradient, indicating the important role of convective turbulence in kinetic fractionation of evaporation. Although the measured εk displays a weak correlation with the slope of the local evaporation line (LEL), by replacing the default εk value of 14.2 ‰ (for 18O) commonly adopted for lake studies, it greatly improves the performance of a theoretical LEL model. The εk data in this study and reported by other authors do not support the hypothesis that εk decreases with increasing lake size. The overall mean εk is 9.7 ‰ for 18O and 8.5 ‰ for 2H, based on nine outdoor experimental results.

Higher reproductive performance of a piscivorous avian predator feeding on lower trophic-level diets on ponds with shorter food chains

Variation in food-chain length may influence a predator’s trophic position. In aquatic food webs, the energy value of prey typically increases with its trophic rank; hence a higher trophic-level diet is often assumed to indicate better habitat quality. We related the body and health condition of pre-fledged Red-necked Grebes Podiceps grisegena to their dietary trophic level (estimated using stable nitrogen isotope signals of feathers) in two managed pond habitats with contrasting prey availability due to different fish population structures. Ponds stocked with young, small common carp Cyprinus carpio provided abundant fish and non-fish (insects and amphibians) resources for chicks. In ponds stocked with large carp, which also supported populations of small predatory fish, the breeding success of grebes was comparatively poor, because carp exceeded the size suitable for chicks and adversely affected non-fish prey. Pre-fledged grebes were in better condition (greater body mass, lower heterophil/lymphocyte ratio) in the food-rich small-fish ponds than in the food-poor ponds dominated by large fish. Values for δ15N suggested shorter food chains and a lower trophic-level diet for grebes in the food-rich ponds. Bayesian carbon and nitrogen isotope mixing models demonstrated the dietary prominence of small fish, both carp and predatory species. Between-habitat differences in food-chain length and grebe trophic position resulted from the higher trophic rank of small predatory fish in the food-poor ponds compared to the omnivorous carp in the food-rich ponds. Our results suggest that in aquatic food webs, feeding at higher trophic levels by strongly size-limited generalist avian predators can be associated with overall food scarcity due to the impact of fish, and thus trophic status cannot be used uncritically as a proxy for aquatic habitat quality.

Pond-adjacent grass height and pond proximity to water influence predation risk of pond fish by amphibians in small fish ponds of Kakamega County, western Kenya

The study investigated predation risk to pond-reared Nile Tilapia Oreochromis niloticus and African Catfish Clarias gariepinus by amphibians, whether this is driven by height of pond-side grass or pond proximity to surface-water source and how this varies with fish stocking options. Based on small-scale freshwater aquaculture farms in western Kenya, field surveys were conducted during three sampling seasons spread across 6 months. These involved the following: (1) a sociological survey of 29 fish farming households; (2) sampling of amphibians for density, species richness and encounter rates and (3) measuring grass height, pond dimensions and water-source proximity across 24 ponds. Overall, 131 individual frogs from three families were recorded in 78 encounters. Amphibian density increased with pond-side grass height, presumably increasing predation risk, but decreased with water-source proximity. Amphibian encounter rate also decreased with water-source proximity, but was unaffected by grass height, while species richness responded positively to pond-side grass height, but not to water-source proximity. Amphibian encounter likelihood was higher in tilapia-only than in catfish-only or tilapia and catfish ponds irrespective of habitat variables. We demonstrate here that management practices for mitigating fish loss to predatory amphibians should include trimming pond-side vegetation, siting ponds close-to-moderate distances from water-sources and including catfish in pond polycultures.

Modeling trophic webs in freshwater fishpond systems using Ecopath: towards better polyculture management

Freshwater pond polyculture faces many challenges in Europe. Appropriate tools must be developed to better understand and manage trophic interactions in pond ecosystems. The objective of our study was to understand the trophic interactions and make inference on the fish diet in common carp polyculture through a combination of experiments and trophic web modeling. We conducted an experiment in small fishponds of common carp polyculture reared with roach and perch and used Ecopath with Ecosim software to characterize the food web. Two replicates of 3 treatments were performed: a semi-extensive pond with low fish density and no formulated feed, an intensive pond with twice the fish density and formulated feed and an intensive pond coupled with a planted lagoon. Ten trophic groups were defined to describe the food web. The modeling procedure enabled us to estimate the diets of each trophic group. The fish diet in fed and non-fed treatments differed greatly since the carp fed mainly on formulated feed when available. The roach exhibited trophic plasticity by adapting their diet to the available resources. The benthic macroinvertebrates and zooplankton were preyed upon intensively; they became the limiting factors for fish production and depended on phytoplankton availability. Detritus and phytoplankton were the main sources of nutrients in all treatments but were not used efficiently. These results provide several insights for improving polyculture. In particular, they promote better management of zooplankton and macroinvertebrates as food sources for target species and a better balance in fish assemblages for more efficient use of resources.

An evaluation of the flux-gradient and the eddy covariance method to measure CH4, CO2, and H2O fluxes from small ponds

Despite their small overall area, small ponds play a large role in the greenhouse gas budgets of inland water bodies. This study aims to evaluate the performance of the flux-gradient (FG) and the eddy covariance (EC) method for measuring the fluxes of CO2, CH4, and H2O at two small fish ponds (fetch < 120 m) in subtropical climate conditions. The EC fluxes were subject to two sources of error: high frequency flux loss and footprint contamination. Of the three gaseous fluxes, the CH4 flux suffered the largest high frequency loss (18%) due to a combination of low EC instrument height and long optical path of the CH4 analyzer. Despite the low measurement height, the EC fluxes were influenced by sources outside the boundary of the target fish ponds, with the footprint contamination most severe on the CO2 flux and least severe on the CH4 flux. With regards to the FG method, one major uncertainty lies in the eddy diffusivity calculation. Of the three eddy diffusivity models evaluated [the aerodynamic (AE) model deploying the full Obukhov stability correction, the modified Bowen-ratio model using H2O as a tracer, and the wind profile model for neutral stability], the AE model yielded the best results for the CO2 and CH4 fluxes. Our results support Horst’s (1999, Boundary-Layer Meteorology 90, 171) theoretical prediction that the footprint of the AE flux based on a two-level concentration profile measurement should be much smaller than that of the gradient flux footprint and the EC flux footprint at the geometric mean of the two heights. We conclude that the most appropriate micrometeorological method for measuring fluxes from small water bodies is a hybrid scheme, whereby an EC system is deployed to measure the eddy diffusivity and a precision gas analyzer is used to obtain the concentration gradient of the target gas.

Disease dynamics of red-spotted newts and their anuran prey in a montane pond community.

Long-term monitoring of amphibians is needed to clarify population-level effects of ranaviruses (Rv) and the fungal pathogen Batrachochytrium dendrobatidis (Bd). We investigated disease dynamics of co-occurring amphibian species and potential demographic consequences of Rv and Bd infections at a montane site in the Southern Appalachians, Georgia, USA. Our 3-yr study was unique in combining disease surveillance with intensive population monitoring at a site where both pathogens are present. We detected sub-clinical Bd infections in larval and adult red-spotted newts Notophthalmus viridescens viridescens, but found no effect of Bd on body condition of adult newts. Bd infections also occurred in larvae of 5 anuran species that bred in our fishless study pond, and we detected co-infections with Bd and Rv in adult newts and larval green frogs Lithobates clamitans. However, all mortality and clinical signs in adult newts and larval anurans were most consistent with ranaviral disease, including a die-off of larval wood frogs Lithobates sylvaticus in small fish ponds located near our main study pond. During 2 yr of drift fence monitoring, we documented high juvenile production in newts, green frogs and American bullfrogs L. catesbeianus, but saw no evidence of juvenile recruitment in wood frogs. Larvae of this susceptible species may have suffered high mortality in the presence of both Rv and predators. Our findings were generally consistent with results of Rv-exposure experiments and support the purported role of red-spotted newts, green frogs, and American bullfrogs as common reservoirs for Bd and/or Rv in permanent and semi-permanent wetlands.

Flood Transformation Effect of a System of Small Water Reservoirs

The paper resumes the investigation of transformation of watershed flow off caused by retention volumes of small water reservoirs (SWR) in landscape. Based on our work experience in the field of water reservoir design and research, we know that simple system of even small fishponds disposes of nonnegligible free retention volume. We decided to verify this assumption with aid of exact determination of discharge transformation within the basin containing realized system of small water reservoirs. The input water management data for design of water reservoirs are represented by water discharge in existing stream related to the point of designed SWR. In the Czech Republic, the data are provided by the Czech Hydrometeorological Institute (CHMI), however the data refer to an unaffected discharges, i.e. without consideration of transformation effects of existing small water reservoirs within the basin. Although the total available volume for transformation purposes of investigated SWR system is relatively small, the results show the transformation effect of such reservoirs is not insignificant. Furthermore the transformation effect is raised by proper design and functionality of the whole system of water reservoirs.

Correction to ‘Habitat connectivity and resident shared predators determine the impact of invasive bullfrogs on native frogs in farm ponds’

You have accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Atobe Takashi, Osada Yutaka, Takeda Hayato, Kuroe Misako and Miyashita Tadashi 2014Correction to ‘Habitat connectivity and resident shared predators determine the impact of invasive bullfrogs on native frogs in farm ponds’Proc. R. Soc. B.2812014128920141289http://doi.org/10.1098/rspb.2014.1289SectionYou have accessCorrectionsCorrection to ‘Habitat connectivity and resident shared predators determine the impact of invasive bullfrogs on native frogs in farm ponds’ Takashi Atobe Takashi Atobe Google Scholar Find this author on PubMed Search for more papers by this author , Yutaka Osada Yutaka Osada Google Scholar Find this author on PubMed Search for more papers by this author , Hayato Takeda Hayato Takeda Google Scholar Find this author on PubMed Search for more papers by this author , Misako Kuroe Misako Kuroe Google Scholar Find this author on PubMed Search for more papers by this author and Tadashi Miyashita Tadashi Miyashita Google Scholar Find this author on PubMed Search for more papers by this author Takashi Atobe Takashi Atobe Google Scholar Find this author on PubMed Search for more papers by this author , Yutaka Osada Yutaka Osada Google Scholar Find this author on PubMed Search for more papers by this author , Hayato Takeda Hayato Takeda Google Scholar Find this author on PubMed Search for more papers by this author , Misako Kuroe Misako Kuroe Google Scholar Find this author on PubMed Search for more papers by this author and Tadashi Miyashita Tadashi Miyashita Google Scholar Find this author on PubMed Search for more papers by this author Published:22 August 2014https://doi.org/10.1098/rspb.2014.1289This article corrects the followingResearch ArticleHabitat connectivity and resident shared predators determine the impact of invasive bullfrogs on native frogs in farm pondshttps://doi.org/10.1098/rspb.2013.2621 Takashi Atobe, Yutaka Osada, Hayato Takeda, Misako Kuroe and Tadashi Miyashita volume 281issue 1786Proceedings of the Royal Society B: Biological Sciences07 July 2014Proc. R. Soc. B281, 20132621 (7 July 2014; Published online 14 May 2014) (doi:10.1098/rspb.2013.2621)Figure 1 on p. 4 was published incorrectly. We have added the causal link from ‘actual abundance of bullfrogs’ to ‘actual abundance of wrinkled frogs’. Figure 1. Bayesian analysis diagram for how the abundance of invasive bullfrogs and native wrinkled frogs are directly and indirectly affected by pond connectivity, carp and local environments. Grey boxes represent estimated parameters and white boxes represent data collected from our field surveys and geographical information systems (GIS). Using a Bayesian hierarchical approach, we estimated detectability of call surveys and unknown distance- and area-dependent parameters, α and β, for connectivity, rather than we fixed them a priori. (Online version in colour.)Download figureOpen in new tabDownload PowerPoint Previous Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsCited by Otieno N, Wasonga D and Imboko D (2021) Pond-adjacent grass height and pond proximity to water influence predation risk of pond fish by amphibians in small fish ponds of Kakamega County, western Kenya, Hydrobiologia, 10.1007/s10750-021-04551-8, 848:8, (1795-1809), Online publication date: 1-May-2021. Related articlesHabitat connectivity and resident shared predators determine the impact of invasive bullfrogs on native frogs in farm ponds07 July 2014Proceedings of the Royal Society B: Biological Sciences This Issue22 August 2014Volume 281Issue 1789 Article InformationDOI:https://doi.org/10.1098/rspb.2014.1289Published by:Royal SocietyOnline ISSN:1471-2954History: Published online22/08/2014Published in print22/08/2014 License:© 2014 The Author(s) Published by the Royal Society. All rights reserved. Citations and impact Large datasets are available through Proceedings B's partnership with Dryad

The impact of using lead pellets on lead contamination of mallards (Anas platyrhynchos) in the Czech Republic

The aim of the study was to assess the degree of lead contamination in mallards in the Czech Republic as a result of using lead shots for wildfowling. Two sites used for mallard hunting were chosen, namely a flood-control reservoir in Moravia and a small fishpond in Bohemia. Lead concentrations were determined in the tissues of 20 mallards (Anas platyrhynchos) raised at those standing open water sites (n = 10 at each site) and killed there during the autumn hunting season with a steel shot. Control groups were made up of 20 mallards from the same breeding facility as experimental groups but raised in an enclosure without access to water (n = 10 at each site). Lead concentrations were determined in selected tissues (breast muscle, heart, liver, gizzard, kidney, feathers - quill base, lung, brain and humerus) by high resolution continuum source atomic absorption spectrometry. The results showed elevated lead concentrations in all tissues of mallards compared with control in the reservoir in Southern Moravia. The highest lead concentrations (mg/kg) were found in the humerus (14.254 ± 4.525 and 5.083 ± 0.748 for experimental and control mallards, respectively). In contrast, lead concentrations in mallards from small fishpond in Southern Bohemia were lower compared to control. Similarly, the highest lead concentrations were found in the humerus (2.219 ± 0.349 and 8.930 ± 1.012 for experimental and control mallards, respectively). This study extends very limited information about lead contamination of wild ducks in the Czech Republic in connection with hunting activities.

Zygnematalean zygospores: Morphological features and use in species identification

Suitable morphological characteristics for identification of zygnematalean algae were determined using a combination of classical light microscopy (LM) techniques, fluorescence microscopy (with blue and green excitation), scanning electron microscopy (SEM) and specialized culture methods. Characteristics of spore germination, growth and reproduction under culture conditions identified Zygnema chalybeo-spermum in a mixture of zygnematalean spores collected from a small fishpond in Czechia. Reproduction in general, particularly aplanospore formation and lateral conjugation was more frequent and occurred earlier in a nutrient poor medium than in a nutrient rich medium, where vegetative growth was more vigorous. Variability in spore size was wide and influenced by the origin (sexual and/or asexual) of the spores. Asexual spores, particularly partenospores were rounded and significantly smaller than sexual ones. Thus spore morphology alone (size and shape) is not a particularly helpful characteristic for species identification. The mesospore of mature spores contained lipids and a sporopolenin-like material (algaenan), which showed green autofluorescence with blue excitation. The mesospore ornamentation, the only characteristic found that is suitable for identification purposes, can be observed easily in LM and SEM after exospore removal by KOH treatment. Detailed LM and SEM observations of the zygospores of all Zygnema species thus could provide basic data necessary for the preparation of an atlas and key for species identification which, after completion with molecular methods, brings clarification into the genetic relationships between morphospecies.

First record of Pipistrellus kuhlii (Chiroptera) from Slovakia

Pipistrellus kuhlii (Kuhl, 1817) has a Palearctic and Afrotropic distribution. It ranges from the Canary Islands eastward to 93◦ E in S Asia, most of Africa and throughout S and W Europe – from the Iberian Peninsula and France to S Germany, Switzerland, Austria, Hungary, the Balkan states and SW Russia (VERNIER & BOGDANOWICZ, 1999; HORACEK et al., 2000; SPITZENBERGER & BAUER, 2001; BOGDANOWICZ, 2004). On 31 May 2006 an adult male P. kuhlii was recorded in City Park of Nitra (Nitrianska pahorkatina Highlands, W Slovakia, 48◦18′ N, 18◦04′ E; 140 m a.s.l.). The bat was caught in a 3.5 m high mist net erected on a bank of a small fishpond (ca. 200 × 80 m) surrounded by willows. External measurements of the bat were: body 43 mm, tail 40 mm, forearm 32.8 mm, hind foot 6 mm, ear 11 mm, tragus 5 mm, 3 finger 58.2 mm, 5 finger 41.2 mm and wingspan 235 mm. The weight was 4.9 g. The bat was yellow-brown in color on the dorsal side of its body; the ears and face were brown. The wing was bordered by a 1–1.5 mm contrasting white margin between the 3 finger and the tail (Fig. 1). The first upper incisor had a single cusp and the second incisor was almost impossible to recognise (15× magnifying glass). At the same location, several Pipistrellus nathusii (Keyserling et Blasius, 1839) were caught simultaneously with the P. kuhlii, so it was possible to compare the characteristics of both these quite similar species. The bat was photographically documented, banded (SLOVAKIA A 0597), allowed to drink and released again in the park, at night, on 4 June 2006. The nearest record of this species is from Vienna, Austria, 130 km W (BOGDANOWICZ, 2004). Nitra is now the most northerly location recorded for this species in C Europe and it is consistent with its anticipated spread northwards (FIEDLER et al., 1999; BOGDANOWICZ, 2004). The occurrence of this species in an urban area was also typical for this species, as it exhibits one of the highest degrees of synanthropy among bat species in Europe (BOGDANOWICZ, 2004). It is interesting that four congeneric species were hunting together in the park: Pipistrellus kuhlii, P. pipistrellus (Schreber, 1774), P. pygmaeus (Leach, 1825) and P. nathusii. Although P. kuhlii was already listed as a member of Slovakian mammal fauna (BABOR, 1943) this was challenged by FERIANC (1946) as unsubstantiated. A Pipistrellus sp. with a white margin on the wing membrane was mistnetted in Kirť (Ipeľska kotlina basin, S Slovakia, 48◦06′ N, Fig. 1. Contrasting white margin on the wing (between the 3rd finger and the tail) is typical character for P. kuhlii.

Answering the Question: “Doctor, if This Were Your Child, What Would You Do?”

Tommy* was only 2 years old when he was admitted to our ICU. He was a bright toddler, full of joy and laughter. His parents loved him dearly, and they cared for him with great affection. Tommy's family did not have a pool, but they did have a small fishpond in the backyard. No one ever thought about putting a fence around the fishpond; how dangerous could such a small pond be? Well, it seems it was quite dangerous, and one morning Tommy's mother found him face down in it. She called 911, and Tommy's heart began beating after prolonged cardiopulmonary resuscitation. He was admitted to our ICU unconscious and unresponsive. Two days went by, and Tommy showed no sign of neurologic recovery. Although his other organ systems improved, he had no purposeful movements. I had been meeting with the parents every day in anticipation of our discussion that day. I explained to Tommy's parents that without some recovery by 48 hours, there was no hope of meaningful recovery after such an event. I explained that we had 2 options: discontinue support, and he would likely die relatively quickly, or continue the ventilator, and his brainstem would regain enough function that he would continue to breathe but would surely remain in a vegetative or minimally conscious state for the rest of his life. Then it came—the question: “Doctor, if he were your child, what would you do?” In 1999, Truog1 wrote a thought-provoking essay in which he distinguished differences between giving advice based on medical facts and giving value-laden advice. Truog also drew our attention to the “gray zone” between these extremes. He argued that although it is appropriate for physicians to give strictly medical advice, it may be less advisable to give advice that is based on … Address correspondence to Alexander A. Kon, MD, Pediatrics and Bioethics, University of California at Davis, 2516 Stockton Blvd, Sacramento, CA 95817. E-mail: aakon{at}ucdavis.edu

Changes in zooplankton structure around illuminated cage culture

In order to mass-scale rearing of coregonid (Coregonidae) larvae and juveniles for restocking purposes, the use of electric light for attraction of zooplankton was developed in Poland. The positive phototactic response in different groups of zooplankton was studied during cage culture experiments. An observation was conducted in three different environments (a pond, the eutrophic Lake Leginskie and the hypereutrophic Lake Mutek) in Northern Poland, to evaluate zooplankton concentration around the light source. The study gives information on changes in zooplankton densities, cumulation cycles, and interaction between planktonic organisms in and around illuminated cages. Particular zooplanktonic organisms varied strongly in different environments in their reaction to light. The water transparency may be responsible for some of these reactions. However, some evolutionary and behavioural patterns should be taken into account.

Fish Introductions in Africa and Some of Their implications

Fish introductions in Africa have been made at various spatial scales from small fish ponds to the largest lakes, primarily to sustain or increase production, though some were to develop sport fisheries and to control unwanted organisms. Some introductions have fulfilled their objective in the short term, but several "successful" introductions have created uncertainties about their long-term sustainability. Lates niloticus, Oreochromis niloticus, O. leucostictus, Tilapia melanopleura and T. zilli were introduced into Lakes Victoria and Kyoga in 1950's and early 1960's; by the 1980's L. niloticus and O. niloticus dominated the fisheries, having virtually eliminated a number of endemic species. In Lake Victoria, the loss of genetic diversity has been accompanied by a loss of trophic diversity; the transformation of the fish community coincided with profound eutrophication (algal blooms, fish kills, hypolimnetic anoxia) which might be related to alterations of the lake's food-web structure. By contrast, the introduction of a planktivore, Limnothrissa miodon into Lake Kivu and the Kariba reservoir has established highly successful fisheries with little effect on the pre-existing fish community or trophic ecology. The endemic species-rich African Great Lakes may be particularly sensitive to introductions. Species extinctions, introgressive hybridization and ecosystem alterations may occur following introductions.

Invasion by the tufted duck Aythya fuligula into a pond area: implications of diffuse competition.

During the 20th century the Tufted Duck (Aythya fuligula) showed an expansion of its distribution to the west in Europe. We present data for a small fish pond system in northern Bavaria indicating that the Tufted Duck is not fully integrated in the already established communities. The possible mechanism producing this effect seems to be "diffuse competition" by a set of species, which forms a densely packed guild.

Management of a Small Fish Pond in Texas

Management of a Small Fish Pond in Texas

Observations on the Behavior of Color-Banded California Thrashers

The following observations on California Thrashers (Toxostoma redivivum) were made from November 8, 1935, to June 2, 1936, and from September 16, 1936, to June 1, 1937, at 241 South Holliston Avenue, Pasadena, California. My banding station was located on the open balcony of our rear second-story apartment. From this balcony and the windows of the apartment, I was able to identify with field glasses color-banded birds over an area of approximately 32,000 square feet, or about three-quarters of an acre, comprising seven back yards of neighboring residences. These casually gardened yards were situated in a pleasant old residential district. Bounded on the east and west by houses, they contained the usual human paraphernalia of cement driveways, garages and sheds. In addition was a varied and favorable bird environment: a dense cypress hedge 15 to 20 feet high and 5 feet thick, which supported many nests, a 50-foot cypress tree, three large untrimmed Washington palms, several large oaks, seven walnut trees, and numerous citrus and deciduous fruit trees. An abandoned dirt tennis court and several fence corners grew abundantly to weeds; morning-glory and honeysuckle vines flourished on two garages and on an old barn. Flower plots, low hedges and dense shrubs completed the picture. Each of the yards had an available water supply, either dripping water faucets, bird baths, or small fish ponds. The winter of 1935-1936 was mild, even for southern California, with moderate rains and few frosts. The winter of 1936-1937 was one of record cold. From Christmas to March, night frosts were almost continuous. Plant damage was heavy. In spite of the fact that children and adults, cats and dogs, and automobiles, frequently occupied the area, a large and healthy bird population maintained itself. Common resident species, beside the thrashers, were Western Mockingbirds, Song Sparrows, Brown and Spotted towhees, and California Jays. A flock of California Quail used the yards as part of their feeding ground and at least two pairs nested in it. House Finches and Gambel Sparrows were periodically numerous; Brewer Blackbirds became numerous the second spring. A Sharp-shinned Hawk was seen in the area only once, when it attacked a trapped sparrow on the balcony. Human residents were indifferent or mildly friendly to the birds. Pet cats were the chief enemies of birds.