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EASTERN RED CEDAR EFFECTS ON SILPHIDAE INCLUDING AMERICAN BURYING BEETLES ( NICROPHORUS AMERICANUS )

EASTERN RED CEDAR EFFECTS ON SILPHIDAE INCLUDING AMERICAN BURYING BEETLES ( NICROPHORUS AMERICANUS ) Thomas L. Walker, Jr. (T. J.) and W. Wyatt Hoback University of Nebraska at Kearney Outline

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EASTERN RED CEDAR EFFECTS ON SILPHIDAE INCLUDING AMERICAN BURYING BEETLES ( NICROPHORUS AMERICANUS )

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  1. EASTERN RED CEDAR EFFECTS ON SILPHIDAE INCLUDING AMERICAN BURYING BEETLES (NICROPHORUS AMERICANUS) Thomas L. Walker, Jr. (T. J.) and W. Wyatt Hoback University of Nebraska at Kearney

  2. Outline • Chapter 2. Effects of Eastern Red Cedar on Capture Rates of Nicrophorus americanus and Other Silphidae • Chapter 3. Effects of eastern red cedar on reproduction of Nicrophorus species • Chapter 4. Mark-and-recapture population estimates and short-term movement patterns of Nicrophorus americanus

  3. Chapter 1. Introduction and Literature Review • Biological Overview of N. americanus • Distribution and Historical Accounts • Known occupied habitats • Potential Causes of Declines • Concerns with local population/cedars/study areas

  4. Life History of Nicrophorus americanus • Taxomomy - Coleoptera: Silphidae: Nicrophorinae • “Carrion Beetle” • “Burying Beetle” • parental care • Univoltine species • Nocturnal - temperature dependent activity

  5. Nebraska Distribution • Recent Records • recent trapping efforts • Historical Records • Pre-1992 • Valentine NWR - 1992 • Peyton’s Shrew Traps - 1994 • Loess Canyons - 1994 • State Fair Specimen - 1994 or 1995 http://ww2.unk.edu/acad/biology/hoback/carrion_beetles

  6. Habitats • Formerly thought to be species of eastern deciduous forest • Current populations are found in: • Rhode Island - grassland, pastures, thickets • Oklahoma/Arkansas - deciduous forest (primarily oak) and grassland mix • Kansas - grassland with scattered woodland • South Dakota/NC Nebraska - open grassland with scattered trees, some riparian forest • SC Nebraska - prairie/juniper woodland

  7. Concerns with Loess Canyons • Cedar encroachment • 30% of rangeland or more • Increasing about 2%/year • Grazing Management • Stocking rates • Timing, duration, intensity • Poor water distribution • Lack of Diversity • CS grasses • forbs, native shrubs • Some landowners are doing nothing • Some are trying to eradicate their cedars

  8. Study Area - Gosnell Site • Privately owned • 97 hectares • Removed cedars from about 33 hectares • Altered grazing management to reduce CS grasses & increase diversity

  9. Study Area - Wapiti WMA • State owned Wildlife Management Area • Purchased in 2004/05 • 777 hectares • Previously abused • Rested in 2005 • Will be managed for elk, mule deer, turkey, mixed grass prairie and N. americanus

  10. Climate of SE Lincoln County • Large temperature variations • Fairly arid, with most precipitation in spring and summer • Prevailing wind from SE in summer

  11. Effects of Eastern Red Cedar on Capture Rates of Nicrophorus americanus and Other Silphidae • GOALS: • To evaluate impact of cedar encroachment on foraging of N. americanus and other silphids • To compare capture rates of N. americanus and other silphids to determine potential for interspecific competition • To measure microhabitat conditions in cedar-dominated and grassland trapping sites for comparison with trapping results

  12. Materials and Methods - Trapping • Modified USFWS Protocol • Paired traps, cedar & open • Laboratory rats for bait • Identified and counted all carrion beetles captured • Sexed and marked ABB

  13. Materials and Methods - Microhabitat Variables • HOBO data loggers • Temperature • Relative Humidity • Dew Point • Light Intensity • Soil Temperature • Hourly Readings through trapping periods • Compared to capture rates • Of N. americanus • Of N. marginatus and N. orbicollis

  14. Results

  15. Results - Capture Statistics (all) Species # #/TN Species # #/TN N. americanus 265 0.51 Ne. surinamensis 1,486 2.90 N. carolinus 62 0.12 Ne. americana 2 0.004 N. guttula* 13 0.03 O. inaequale 32 0.06 N. marginatus 14,803 28.91 O. novaboracense 16 0.03 N. obscurus 22 0.04 T. lapponicus 794 1.55 N. orbicollis 5,906 11.54 T. truncatus 806 1.57 N. pustulatus 16 0.03 Silphinae 3,136 6.13 N. tomentosus 6,960 13.59 Nicrophorus 28,047 54.78 * denotes new county record All Silphidae 31,183 60.90

  16. Results - Capture Statistics (by habitat) Species Open Cedar Species Open Cedar N. americanus 152A 113 Ne. surinamensis 876A 610 N. carolinus 36 26 Ne. americana 0 2 N. guttula 10 3 O. inaequale 17 15 N. marginatus 10,489A 4,314 O. novaboracense 7 9 N. obscurus 18 4 T. lapponicus 602A 192 N. orbicollis 1,632A 4,274 T. truncatus 580A 226 N. pustulatus 4 12 Silphinae 2,082 1,054 N. tomentosus 2,715 4,245 Nicrophorus 15,056 12,991 A significant difference P < 0.05 All Silphidae 17,138A 14,045

  17. Relative Abundance of Nicrophorinae • N. marginatus 56 X • N. tomentosus 26 X • N. orbicollis 22 X • N. carolinus 0.2 X • N. obscurus 0.08 X • N. pustulatus 0.06 X* • N. guttula 0.05 X • Potential competition for carrion during reproduction • * - N. pustulatus is a brood parasite • Potential competition for food with all listed

  18. Other Competitors? • Silphinae - good #’s • different life cycle • feed on fly larvae and carrion • Dung Beetles? • Obviously feed on carrion • large #’s in some traps • at least 5 species

  19. Microhabitat Variables and Capture Rates • Air Temperature - no relationships with captures • daily high, nightly low, at sunset or sunset + 2 hours • Relative Humidity - no relationships with captures • daily low, nightly high, at sunset or sunset + 2 hours • Dew Points - no relationships with captures • combination of temperature and relative humidity • Light Intensity - no relationships with captures • nightly readings essentially zeroed out every night at all HOBO data logger locations

  20. Microhabitat Variables and Capture Rates (continued) Positive but weak relationships between temperature and capture rates.

  21. Microhabitat Variables and Capture Rates (continued) Humidity had little impact upon capture rates.

  22. Microhabitat Variables vs. Habitat Type (Temperature)

  23. Microhabitat Variables vs. Habitat Type (Relative Humidity)

  24. Microhabitat Variables vs. Habitat Type (Light Intensity)

  25. Conclusions - Capture Rates • Cedars limit or reduce ABB captures • suggests that detection of prey may be reduced or that N. americanus does not like cedars • relationship not significant with recaptures included • possible artifact of bait conditions • Open grassland preferred by N. marginatus, T. lapponicus, T. truncatus, & Ne. surinamensis • Cedar habitats preferred by N. orbicollis • encroachment may be increasing competition

  26. Conclusions - Interspecific Competition • N. marginatus, N. tomentosus and N. orbicollis all greatly outnumber N. americanus • First two species diurnal, N. tomentosus breeds late • N. orbicollis nocturnal - could be threat as competitor • N. carolinus, N. obscurus, N. pustulatus and N. guttula low numbers - not much competition • Silphinae - Fair numbers, may compete some • different life cycles and feeding strategies • Dung Beetles - large numbers feeding on carrion bait

  27. Conclusions - Microhabitat Variables • No relationships between temperature, relative humidity, dew points or light intensity and capture rates of N. americanus, N. marginatus or N. orbicollis. • Somewhat surprising as Bedick (1997) found high temperatures and low humidity lethal for N. marginatus • Temperature and relative humidity conditions should be better for burying beetles in cedar-dominated habitats. • Light intensity lower in cedars during day, no difference at night - Light pollution should not be a problem.

  28. Effects of eastern red cedar on reproduction of Nicrophorus species • GOALS: • To determine effects of cedar trees on reproduction of N. marginatus • To determine effects of cedar trees on microhabitat variables that can influence breeding success of Nicrophorus species

  29. Materials and Methods - “Brood Ball” Sets • Captured N. marginatus in baited pitfall traps, separated them by sex (by counting abdominal segments) • Placed pairs with suitable carrion in cedar-dominated and grassland habitats - 56 in each habitat over 2 years • placed beneath inverted flower pots within emergence cages • Checked carcass condition (buried, not buried, or missing) after 1 day, then weekly for 6-7 weeks • Extracted 1 brood ball per study area and habitat type at 1 week, waited for remainder to progress to emergence or fail • Recorded known and probable successes, losses and causes of losses

  30. Materials and Methods - Microhabitat Variables • Recorded the following microhabitat variables and compared them by habitat type: • Soil temperature • Soil moisture • Soil compaction • Soil pH • Litter type and depth

  31. When all went well….. Freshly emerged, teneral N. marginatus N. marginatus brood ball

  32. Results - Brood Balls Known Suspected Total Success Success Success Habitat Cedar 5 21 26 (46%)A Open 5 5 10 (18%) Year 2004 5 20 25 (45%) 2005 5 6 11 (20%) Totals 10 26 36 (32%) A Chi-square test, P < 0.01

  33. Results - Brood Balls (Causes of Losses) Insects Congeners Mammals Heat Unknown Habitat Cedar 11 12 5 0 2 Open 15 13 3 13 2 Year 2004 7 0 8 13 3 2005 19 25 0 0 1 Totals 26 25 8 13 4

  34. Results - Microhabitat Variables Carcass Soil Properties Burial Depth Comp. Temp. Moist. (cm) (PSI) (°C) (%)A Habitat Cedar 8.7 402B 21.4B 65%B Open 10.3 549 25.3 59% A Soil moisture measured as percent relative saturation. B Mann-Whitney Rank Sum Test (P < 0.05)

  35. Conclusions - Brood Ball Success • Greater success of brood balls in cedar habitats likely due to a variety of factors: • Natural Factors • Soil compaction (easier burial) • Soil/air temperature (decay of carcass) • Losses to competitors (insects, congeners, mammals) were very similar between habitats • Unnatural Factor • Clay Flowerpots

  36. Conclusions - Brood Ball Success • Cedar trees provide conditions advantageous to breeding of Nicrophorus species • soil temp, moisture, compaction • but too many cedars would likely result in negative impacts due to a loss of diversity and abundance of potential prey items • Soil Compaction - Livestock activity limited to open areas, has compacted soils there • reduced stocking rates, or resting pastures might reduce these differences somewhat • native shrub thickets could also provide similar benefits

  37. Mark-and-recapture population estimates and short-term movement patterns of Nicrophorus americanus • GOALS • To utilize mark and recapture to document short-term movements during trapping periods • To utilize mark and recapture to estimate population sizes for the study area and Loess Canyons area of SE Lincoln County, Nebraska • To evaluate current radio telemetry technology for N. americanus research and document movements and daytime habitat use

  38. Materials and Methods - Mark and Recapture • Beetles were captured as described previously • Each N. americanus was marked with different combination of paint dots • Testors Model Car Paint • Released 200-800m away • Recaptures were recorded and distances determined from GPS locations of traps

  39. Materials and Methods - Population Estimates • Utilized the program “Ecostat” (Young and Young 1998) to do population estimates • Mt Model - Closed population mark-recapture data • Assumes variation through time in capture probabilities • Sensitive to changes in #’s, weather and other variables • Did one population estimate per trapping period • Used 1 km attraction radius to estimate area surveyed and to extrapolate population #’s for Loess Canyons • 1,943 km2 of potentially suitable habitat (Bedick et al. 1999)

  40. Trapping Area (1 km radius around traps)

  41. Materials and Methods - Telemetry Study • Transmitters - Micro-Pips (Biotrack, Ltd.) • Approximately 0.5 grams • Smaller than the pronotum of N. americanus • Approximately 8 X 10 X 3 mm, with 7 cm antenna • Last 7-10 days, detection distance up to 3,200 meters • Attachment • various glues, epoxies, paints and resins in 2004 • Poncho and vest attempts in 2005 • Receivers/Antennas • Receiver • 3-element hand held Yagi

  42. Results - Mark and Recapture Data Trapping # Recaptures Mean Initial Same Period Marked Ind’s (total) Distance TOC Habitat June 04 35 9 (9) 1.185 km 2 5 Aug 04 32 12 (14) 0.328 km 6 8 June 05 68 22 (35) 0.493 km 17 23 Aug 05 65 13 (14) 0.444 km 3 6 Totals 200 56 (72) 0.538 km 28 42

  43. Mark and Recapture - Movements • 3 movements between study areas • 6.2 km movement in 4 days • 5.5 km movement overnight • 4.8 km movement in 5 days • 8 movements 1.2 to 1.5 km within study areas • 14 movements 0.5 to 0.8 km • 19 movements of 33 to 154 m • 28 “zero” movements

  44. Mark and Recapture - Other Statistics • Times recaptured • 45 once, 7 twice, 3 three times, 1 four times • 7 marked N. americanus in one trap on same day • Days between captures • average of 1.76 days between captures • 48 one day, 14 two days, 2 three days, 3 four days, 2 five days, 1 six days, 2 seven days • One N. americanus captured 5 times in 5 days (3 traps) • One 3 times in 8 days (same trap)

  45. Results - Population Estimates Trapping Study Area Pop. 95% Confidence Regional Period Est. + 1 St. Dev Interval Pop. Est. June 04 75 + 19.0 52 - 133 11,184 Aug 04 120 + 25.1 86 - 190 17,894 June 05 118 + 13.2 99 - 152 17,546 Aug 05 322 + 75.5 215 - 522 48,016

  46. Results - Telemetry Study • 3 senescent males in 2004 • one would not fly - struggled in grass - released • one flew 75 m, transmitter was found <10 m from landing point (where beetle burrowed into ground) • final one flew 150 m, was found less than 30 m from TOC next morning after having been captured and consumed by a bat • 3 teneral beetles in 2005 • no flight over 10 m • one moved < 5 m from release point in 2 nights • one moved about 50 (on ground) in 2 nights • one transmitter failed

  47. Problems - Transmitter Attachment

  48. Problems - Transmitter Attachment • Waxy substance exuded by beetles • released to keep beetles clean • makes glues useless • reason for “poncho” and “vest” attachment attempts • Raised profile with transmitter • burying beetles frequently burrow or crawl through and under vegetation, sticks, etc. • raised profile prevents these activities

  49. Conclusions - Mark and Recapture • N. americanus are capable of long-distance movements • Majority of movements (85%) less than 1.0 km, just 3 movements over 1.5 km • Number of multiple recaptures, and recaptures up to 8 days after initial capture, suggest that trapping and marking methods are not harming beetles

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