Animal Sciences Commons^™

Torpor And Other Physiological Adaptations Of The Badger (Taxidea-Taxus) To Cold Environments, Henry Harlow

Henry Harlow

Oxygen consumption (Vo2) and heart rate were measured at ambient temperatures between +20 and -40 C. Basal metabolic rate was 0.3 cm3/g*h (65 beats/min), the body temperature was 38 C, the lower critical temperature (Tlc) was 10 C, and conductance was 0.01225 cm3/g*hoC. Fat composition of 79 adult badgers captured during the winter showed maximal fat deposition of 31% body weight in November. Fat stores were reduced 37% between November and March. The burrow temperature remained between 0 and 4 C throughout the winter. Badgers in outdoor enclosures during the winter of 1977-1978 reduced their above-ground exposure by 93% from …

Metabolic Adaptations To Prolonged Food-Deprivation By The American Badger Taxidea-Taxus, Henry Harlow

Henry Harlow

Energy expenditures for food processing, maintenance, and activity requirements were determined in the laboratory on the American badger, Taxidea taxus, both with ad lib. food and starved for 7, 20, and 30 days. Body weight decreased at about 76 g per day, resulting in a respiratory quotient (RQ) of 0.83 after 30 days of starvation. Energy requirements were calculated from Vo2 values. A 24.2%, 19.7%, and 26.3% reduction in total metabolism was observed at 7, 20, and 30 days, respectively, without food because of reduced maintenance and activity requirements. As a result, badgers were able to conserve approximately 17 g …

Avoidance Of Skeletal Muscle Atrophy In Spontaneous And Facultative Hibernators, Henry Harlow

Henry Harlow

Smooth and skeletal muscle changes were compared from overwintering white-tailed prairie dogs, spontaneous hibernators that undergo regular, low-temperature torpor bouts, and black-tailed prairie dogs, facultative hibernators that use sporadic, moderate-temperature torpor bouts. The objectives were to assess the abilities of these two species with dramatically different torpor patterns (1) to conserve skeletal muscle morphology, protein, and strength and (2) to use labile protein in the small intestine and liver during the winter season of reduced activity and food intake. Mass and protein concentration of the extensor digitorum longus (EDL), soleus, liver, and small intestine, as well as skeletal muscle strength …

Hibernating Bears Conserve Muscle Strength And Maintain Fatigue Resistance, T. D. Lohuis, Henry Harlow, T. Di Beck, P. A. Iaizzo

Henry Harlow

Black bears spend several months each winter confined to a small space within their den without food or water. In nonhibernating mammals, these conditions typically result in severe muscle atrophy, causing a loss of strength and endurance. However, an initial study indicated that bears appeared to conserve strength while denning. We conducted an in vivo, nonsubjective measurement of strength, resistance to fatigue, and contractile properties on the tibialis anterior muscle of six hibernating bears during both early and late winter using a rigid leg brace and foot force plate. After 110 d of anorexia and confinement, skeletal muscle strength loss …

Protein Use And Muscle-Fiber Changes In Free-Ranging, Hibernating Black Bears, D. B. Tinker, Henry Harlow, T. Di Beck

Henry Harlow

Studies of the metabolic and physiological changes that bears undergo during hibernation have, for the most part, supported the paradigm that bears use only fatty tissues as a metabolic substrate during hibernation. This study was performed to document the extent of protein loss and alteration of muscle-fiber characteristics of selected muscles in black bears during winter dormancy. Muscle biopsies were removed from the gas trocnemius and biceps femoris from seven free-ranging female black bears on the Uncompahgre Plateau in west-central Colorado. Six of the seven bears produced cubs during the hibernating season. Muscle samples were collected from the left hind …

Hummingbirds Fuel Hovering Flight With Newly Ingested Sugar, K. C. Welch, B. H. Bakken, Carlos Martinez Del Rio, R. K. Suarez

Carlos Martinez del Rio

We sought to characterize the ability of hummingbirds to fuel their energetically expensive hovering flight using dietary sugar by a combination of respirometry and stable carbon isotope techniques. Broadtailed hummingbirds (Selasphorus platycercus) were maintained on a diet containing beet sugar with an isotopic composition characteristic of C3 plants. Hummingbirds were fasted and then offered a solution containing cane sugar with an isotopic composition characteristic of C4 plants. By monitoring the rates of CO2 production and O-2 consumption, as well as the stable carbon isotope composition of expired CO2, we were able to estimate the relative contributions of carbohydrate and fat, …

The Cyanogenic Glycoside Amygdalin Does Not Deter Consumption Of Ripe Fruit By Cedar Waxwings, H. M. Struempf, J. E. Schondube, Carlos Martinez Del Rio

Carlos Martinez del Rio

Cyanogenic glycosides are common secondary compounds in ripe fruits that are dispersed by birds. These substances are toxic to some mammals. We examined the repellent effect of amygdalin, a cyanogenic glycoside, on Cedar Waxwings (Bombycilla cedrorum). Amygdalin did not reduce food ingestion in Cedar Waxwings, even at relatively high concentrations. In addition, these birds did not exhibit preference for amygdalin-free over amygdalin-containing fruit. Cedar Waxwings given artificial food that contained four times the amount of amygdalin found in some wild fruits ingested the equivalent of 5.5 times the oral lethal dose for rats in 4 h without exhibiting any external …

The Fate Of Carbon In Growing Fish: An Experimental Study Of Isotopic Routing, L. J. Kelly, Carlos Martinez Del Rio

Carlos Martinez del Rio

The application of stable isotope analysis to ecology requires estimating the contribution of different isotopic sources to the isotopic signatures of an animal's tissues using mixing models. These models make the physiologically unrealistic assumption that assimilated nutrients are disassembled into their elemental components and that these atoms are then reassembled into biomolecules. We quantified the extent to which mixing models yield erroneous results with an experiment using Nile tilapia (Oreochromis niloticus). The tilapia were fed synthetic diets that varied in protein content and in which the carbon isotopic composition of protein differed widely from that of carbohydrates and lipids. We …

Dietary Flexibility And Intestinal Plasticity In Birds: A Field And Laboratory Study, P. Sabat, F. Novoa, F. Bozinovic, Carlos Martinez Del Rio

Carlos Martinez del Rio

The adaptive modulation hypothesis posits that the expression of digestive proteins should be modulated in response to intake of their respective substrates. A corollary of this hypothesis suggests that dietary flexibility and digestive plasticity should be correlated. We examined these two hypotheses in two granivorous Chilean birds (Zonotrichia capensis and Diuca diuca) that differ in dietary breadth. D. diuca is a strict granivore, whereas Z. capensis also eats insects. In field-caught birds, the activity of the intestinal dipeptidase aminopeptidase-N was positively correlated with intake of insects in Z. capensis but not in D. diuca. This is the first field documentation …

It Takes Guts (And More) To Eat Fruit: Lessons From Avian Nutritional Ecology, D. J. Levey, Carlos Martinez Del Rio

Carlos Martinez del Rio

No abstract provided.

Are Hummingbirds Facultatively Ammonotelic? Nitrogen Excretion And Requirements As A Function Of Body Size, T. J. Mcwhorter, D. R. Powers, Carlos Martinez Del Rio

Carlos Martinez del Rio

Most birds are uricotelic. An exception to this rule may be nectar-feeding birds, which excrete significant amounts of ammonia under certain conditions. Although ammonia is toxic, because it is highly water soluble its excretion may be facilitated in animals that ingest and excrete large amounts of water. Bird-pollinated plants secrete carbohydrate- and water-rich floral nectars that contain exceedingly little protein. Thus, nectar-feeding birds are faced with the dual challenge of meeting nitrogen requirements while disposing of large amounts of water. The peculiar diet of nectar-feeding birds suggests two hypotheses: (1) these birds must have low protein requirements, and (2) when …

Does Gut Function Limit Hummingbird Food Intake?, T. J. Mcwhorter, Carlos Martinez Del Rio

Carlos Martinez del Rio

Many nectar-feeding bird species decrease food intake when sugar concentration in food is increased. This feeding response can be explained by two alternative hypotheses: compensatory feeding and physiological constraint. The compensatory feeding hypothesis predicts that if birds vary intake to maintain a constant energy intake to match energy expenditures, then they should increase intake when expenditures are increased. Broad-tailed hummingbirds were presented with sucrose solutions at four concentrations (292, 584, 876, and 1,168 mmol L-1) and exposed to two environmental temperatures (10 degrees and 22 degrees C). Birds decreased volumetric food intake in response to sugar concentration. However, when they …

Do Nectar- And Fruit-Eating Birds Have Lower Nitrogen Requirements Than Omnivores? An Allometric Test, E. Tsahar, Z. Ara, I. Izhaki, Carlos Martinez Del Rio

Carlos Martinez del Rio

We used an allometric approach to compare the minimum nitrogen requirements (MNR) and the total endogenous nitrogen loss (TENL) of nectar- and fruit-eating birds with those of omnivorous birds. These two parameters were 4x higher in omnivores than in nectarivores and frugivores. In nectarivorous-frugivorous birds, MNR was 152.8 mg N kg(-0.76) day(-1); in omnivorous birds, it was 575.4 mg N kg(-0.76) day(-1). Similarly, TENL was 54.1 mg N kg(-0.69) day(-1) in nectarivores-frugivores, and 215.3 mg N kg(-0.69) day(-1) in omnivores. The residuals of the allometric relationships between TENL and MNR and body mass were positively correlated, which suggests that a …

Are The Low Protein Requirements Of Nectarivorous Birds The Consequence Of Their Sugary And Watery Diet? A Test With An Omnivore, E. Tsahar, Carlos Martinez Del Rio, Z. Arad, J. P. Joy, I. Izhaki

Carlos Martinez del Rio

Nectar-feeding birds have remarkably low nitrogen requirements. These may be due either to adaptation to a low-protein diet or simply to feeding on a fluid diet that minimizes metabolic fecal nitrogen losses. We measured minimal nitrogen requirements (MNR) and total endogenous nitrogen loss (TENL) in the omnivorous European starling Sturnus vulgaris, fed on an artificial nectar-like fluid diet of varying concentrations of sugar and protein. The MNR and TENL of the birds were similar and even slightly higher than allometrically expected values for birds of the starlings' mass (140% and 103%, respectively). This suggests that the low measured nitrogen requirements …

Comparative Plasma And Urine Chemistry Of Fasting White-Tailed Prairie Dogs (Cynomys-Leucurus) And American Martens (Martes-Americana) : Representative Fat-Bodied And Lean-Bodied Animals, Henry Harlow, Steven Buskirk

Steven Buskirk

American martens and white-tailed prairie dogs are mammals of similar body mass, exposed to periods of food deprivation, but of vastly different body fat content. While both species demonstrated a protein conservation phase during a short-term fast, martens had a greater reliance on protein as depicted by greater loss of body weight, higher daily urine volume, and glomerular clearance rates, as well as higher daily urinary urea excretion. Protein use was calculated to be 3.15 and 1.23 g/d for martens and prairie dogs, respectively. Martens did not hydrolyze a greater amount of urea as they were hypothesized to do in …

Using Historical Dna To Characterize Hybridization Between Baltimore Orioles (Icterus Galbula) And Bullock's Orioles (I. Bullockii), Matthew Carling, L. G. Serene, I. J. Lovette

Matthew Carling

Studies of genetic variation across hybrid zones have demonstrated that the evolutionary dynamics within them are often complicated. Using DNA extracted from toe pads of 701 individuals collected by Sibley and Short (1964) about 50 years ago from across the Icterus bullockii-I. galbula hybrid zone, we calculated mitochondrial cline shape parameters and compared them with plumage-based inferences of the hybrid-zone structure. Genetic and hybrid index score clines, estimated from populations collected along the Platte River in Nebraska, were both concordant (equal widths) and coincident (same center). More generally, the proportion of I. bullockii haplotypes within a sampling locality was strongly …

Obligatory Urea Production And The Cost Of Living In The Magadi Tilapia Revealed By Acclimation To Reduced Salinity And Alkalinity, C. M. Wood, P. Wilson, Harold Bergman, A. N. Bergman

Harold Bergman

Alcolapia grahami is a unique ureotelic tilapia that lives in the highly alkaline, saline Lake Magadi, Kenya (pH, similar to 10.0; alkalinity, similar to380 mmol L-1; Na+, similar to350 mmol L-1; Cl-, similar to110 mmol L-1; osmolality, similar to580 mosm kg(-1)). The fish survived well upon gradual exposure to dilute lake water (down to 1%, essentially freshwater). Urea excretion continued, and there was no ammonia excretion despite favorable conditions, indicating that ureotelism is obligatory. Levels of most ornithine-urea cycle enzymes in the liver were unchanged relative to controls kept for the same period in 100% lake water. The fish exhibited …

Respiratory Physiology Of The Lake Magadi Tilapia (Oreochromis Alcalicus Grahami), A Fish Adapted To A Hot, Alkaline, And Frequently Hypoxic Environment, A. Narahara, Harold Bergman, P. Laurent, J. N. Maina, P. J. Walsh, C. M. Wood

Harold Bergman

The tilapia Oreochromis alcalicus grahami is a unique ureotelic teleost, that only fish that lives in the alkaline hotsprings of Lake Magadi, Kenya. Physical conditions and fish behavior were monitored in the Fish Springs Lagoon area, a site where the tilapia were particularly abundant. Water Po-2 and temperature fluctuated more or less in parallel in a diurnal cycle from less than 20 Torr and less than 25 degrees C at night to greater than 400 Torr and 38 degrees C during the day, whereas pH remained constant at approximately 9.8. Field laboratory tests demonstrated that routine Mo-2 (under normoxia) increased …

Responses Of An Amazonian Teleost, The Tambaqui (Colossoma Macropomum), To Low Ph In Extremely Soft Water, C. M. Wood, R. W. Wilson, R. J. Gonzalez, M. L. Patrick, Harold Bergman, A. Narahara, A. L. Val

Harold Bergman

Our goal was to compare the internal physiological responses to acid challenge in an acidophilic tropical teleost endemic to dilute low-pH waters with those in nonacidophilic temperate species such as salmonids, which have been the subject of most previous investigations The Amazonian tambaqui (Colossoma macropomum), which migrates between circumneutral water and dilute acidic "blackwater" of the Rio Negro, was exposed to a graded low-pH and recovery regime in representative soft water (Na+ = 15, Cl- = 16, Ca2+ = 20 mu mol L-1). Fish were fitted with arterial catheters for repetitive blood sampling. Water PH was altered from 6.5 (control) …

Effects Of Water Ph And Calcium Concentration On Ion Balance In Fish Of The Rio Negro, Amazon, R. J. Gonzalez, C. M. Wood, R. W. Wilson, M. L. Patrick, Harold Bergman, A. Narahara, A. L. Val

Harold Bergman

We examined the effects of acute low-pH exposure on ion balance (Na+, Cl-, K+) in several species of fish captured from the Rio Negro, a dilute, acidic tributary of the Amazon. At pH 5.5 (untreated Rio Negro water), the four Rio Negro species tested (piranha preta, Serrasalmus rhombeus; piranha branca, Serrasalmus cf. holandi; aracu, Leporinus fasciatus; and pacu, Myleus sp.) were at or near ion balance; upon exposure to pH 3.5, while Na+ and Cl- loss rates became significant, they were relatively mild. In comparison, tambaqui (Colossoma macropomum), which were obtained from aquaculture and held and tested under the same …

A New Species Of The Red Crossbill (Fringillidae: Loxia) From Idaho, Craig Benkman, J. W. Smith, P. C. Keenan, T. L. Parchman

Craig Benkman

The Red Crossbill (Loxia curvirostra complex) endemic to the South Hills and Albion Mountains in southern Idaho has coevolved in a predator-prey arms race with the lodgepole pine (Pines contorta latifolia). The resulting divergent selection has favored a sedentary, locally adapted crossbill population whose size and vocalizations differ from those of co-occurring Red Crossbills of other call types. It has also led to high levels of reproductive isolation between the "South Hills crossbill" and nomadic taxa with different vocalizations that move in and out of the area yearly. Genetic analyses of amplified fragment length polymorphisms (AFLP) indicate that about 5% …

Ion And Acid-Base Balance In Three Species Of Amazonian Fish During Gradual Acidification Of Extremely Soft Water, R. W. Wilson, C. M. Wood, R. J. Gonzalez, M. L. Patrick, Harold Bergman, A. Narahara, A. L. Val

Harold Bergman

Sensitivity to acid water was assessed in three species of Amazonian fish that encounter naturally acidic blackwaters to differing degrees in the wild: tambaqui (Colossoma macropomum), matrincha (Brycon erythropterum), and tamoata (Hoplosternum littorale), in decreasing order of occurrence in blackwater. Fish were exposed to a graded reduction in water pH, from pH 6 to 5 to 4 to 3.5, followed by return to pH 6. Fish were exposed to each new pH for 24 h. During these exposures, net transfers of ions (Na+, K+, Cl-, and Ca2+) and acid-base equivalents to and from the external water were used as physiological …

Isolation And Decline Of A Population Of The Orange-Breasted Falcon, R. B. Berry, Craig Benkman, A. Muela, Y. Seminario, M. Curti

Craig Benkman

Probably always rare and local because of its ecology and specialized habitat, the small, isolated population of the Orange-breasted Falcon (Falco deiroleucus) in Belize and Guatemala, likely numbering fewer than 40 territorial pairs, appears to be in steep decline in Belize. Territory occupancy (n = 12 eyries) in the population we studied in Belize declined from 83% (1992 to 1997) to 54% (2003 to 2009), and occupancy in 2009 was only half the mean in the prior decade. Mean annual production of fledglings per territorial pair declined 35% from 0.77 to 0.50. Mean annual population productivity, which measures the combined …

Discordance Between Genetic Structure And Morphological, Ecological, And Physiological Adaptation In Lake Magadi Tilapia, P. J. Wilson, C. M. Wood, P. J. Walsh, A. N. Bergman, Harold Bergman, P. Laurent, B. N. White

Harold Bergman

The Magadi tilapia (Alcolapia grahami, formerly Oreochromis alcalicus grahami) is a remarkable example of teleost life in an extreme environment. Typical conditions include water, pH=10, titration alkalinity >300 mM, osmolality=525 mOsm, temperatures ranging from 23degrees to 42degreesC, and O-2 levels fluctuating diurnally between extreme hyperoxia and anoxia. A number of relatively small tilapia populations are present in various thermal spring lagoons around the margin of the lake separated by kilometers of solid trona crust (floating Na2CO3) underlain by anoxic water. Despite the apparent isolation of different populations, annual floods may provide opportunities for exchange of fish across the surface of …

Call Imitation And Call Modification In Red Crossbills, Patrick C. Keenan, Craig Benkman

Craig Benkman

Open-ended learning of flight calls has been found consistently in the subfamily Carduelinae. Understanding call learning is especially important in Red Crossbills (Loxia curvirostra complex) because calls appear to play an instrumental role in assortative mating, perhaps by acting as a marker trait that signals ecological adaptation for foraging on a particular species of conifer. We analyzed flight call recordings from a banded population of the South Hills (call type 9) crossbill to examine whether young birds imitate the calls of their parents and whether, as adults, individuals modify their calls to match those of their mates. The calls of …

Low Levels Of Population Genetic Structure In Pinus Contorta (Pinaceae) Across A Geographic Mosaic Of Co-Evolution, T. L. Parchman, Craig Benkman, B. Jenkins, C. A. Buerkle

Craig Benkman

Premise of the study : Population genetic analyses provide information on the population context in which evolutionary processes operate and are important for understanding the evolution of geographically variable traits. Earlier studies showed that cone structure of lodgepole pine in the Rocky Mountains diverged among populations because of geographic variation in co-evolutionary interactions involving mammalian and avian seed predators. Analyses of population genetic variation are needed to determine whether this divergence has arisen despite extensive gene flow and whether populations to the east and west of the Rocky Mountains have evolved convergent phenotypes independently. Methods : We investigated genetic structuring …

Cone And Seed Trait Variation In Whitebark Pine (Pinus Albicaulis; Pinaceae) And The Potential For Phenotypic Selection, R. Garcia, A. M. Siepielski, Craig Benkman

Craig Benkman

Phenotypic variation among, individuals is necessary for natural selection to operate and is therefore essential for adaptive evolution. However, extensive variation within individuals can mask variation among individuals and weaken the potential for selection. Here we quantify variation among within individuals in female cone and seed traits of whitebark pine (Pinus albicaulis). In many plants the production of numerous reproductive structures creates the potential for considerable variation within a plant. but these same traits should also undergo strong selection because of their direct link to plant fitness. We found about twice as much variation among individuals (overall mean = 65.3 …

Climate's Role In Polar Bear Past [Letters], Kurt E. Galbreath, Joseph A. Cook, Eric P. Hoberg

Harold W. Manter Laboratory of Parasitology: Faculty and Staff Publications

Striking temporal concordance between the new date for divergence of polar bears and persistent freezing of the Arctic Ocean suggests that this may be one of relatively few instances in which a specific paleoclimatological episode can be convincingly linked to a specific evolutionary event, and it provides vivid demonstration of climatic forcing as a determinant of diversification in biological systems.

Nebraska Bird Review (June 2012) 80(2), Whole Issue

Nebraska Bird Review

Spring Field Report, March 2012 to May 2012 ... 46

Snowy Owl Invasion of 2011–12 ... 72

Spring Field Days and Annual Meeting at Broken Bow, May 18–20, 2012 ... 77

[Correction … 77]

Subscription and Organization Information ... 83

Snowy Owl Invasion Of 2011–12, Joel G. Jorgensen, Lauren R. Dinan, Thomas J. Walker Jr.

Nebraska Bird Review

The Snowy Owl (Bubo scandiacus) is an Arctic breeder that regularly migrates to and winters in southern Canada and the northern United States (Parmalee 1992). The number of Snowy Owls moving south and the extent and timing of southward movements in any one year are believed to be dependent on interactions between populations of Snowy Owls and lemmings, the owls’ principal food resource (Parmalee 1992). Infrequently, relatively large numbers of Snowy Owls are observed in areas or regions where few are typically observed, and individuals are observed well south of the normal winter range. These occurrences are often …