Published on January 19, 2008
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: 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 Chapter 1. Introduction and Literature Review: 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 Life History of Nicrophorus americanus: Life History of Nicrophorus americanus Taxomomy - Coleoptera: Silphidae: Nicrophorinae “Carrion Beetle” “Burying Beetle” parental care Univoltine species Nocturnal - temperature dependent activity Nebraska Distribution: Nebraska Distribution 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 Recent Records recent trapping efforts Habitats: 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 Concerns with Loess Canyons: 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 Study Area - Gosnell Site: Study Area - Gosnell Site Privately owned 97 hectares Removed cedars from about 33 hectares Altered grazing management to reduce CS grasses & increase diversity Study Area - Wapiti WMA: 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 Climate of SE Lincoln County: Climate of SE Lincoln County Large temperature variations Fairly arid, with most precipitation in spring and summer Prevailing wind from SE in summer Effects of Eastern Red Cedar on Capture Rates of Nicrophorus americanus and Other Silphidae: 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 Materials and Methods - Trapping: 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 Materials and Methods - Microhabitat Variables: 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 Slide14: Results Results - Capture Statistics (all): 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 Results - Capture Statistics (by habitat): 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 Relative Abundance of Nicrophorinae: 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 Other Competitors?: 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 Microhabitat Variables and Capture Rates: 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 Microhabitat Variables and Capture Rates (continued): Microhabitat Variables and Capture Rates (continued) Positive but weak relationships between temperature and capture rates. Microhabitat Variables and Capture Rates (continued): Microhabitat Variables and Capture Rates (continued) Humidity had little impact upon capture rates. Microhabitat Variables vs. Habitat Type (Temperature): Microhabitat Variables vs. Habitat Type (Temperature) Microhabitat Variables vs. Habitat Type (Relative Humidity): Microhabitat Variables vs. Habitat Type (Relative Humidity) Microhabitat Variables vs. Habitat Type (Light Intensity): Microhabitat Variables vs. Habitat Type (Light Intensity) Conclusions - Capture Rates: 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 Conclusions - Interspecific Competition: 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 Conclusions - Microhabitat Variables: 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. Effects of eastern red cedar on reproduction of Nicrophorus species: 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 Materials and Methods - “Brood Ball” Sets: 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 Materials and Methods - Microhabitat Variables: 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 When all went well…..: When all went well….. N. marginatus brood ball Freshly emerged, teneral N. marginatus Results - Brood Balls: 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 Results - Brood Balls (Causes of Losses): 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 Results - Microhabitat Variables: 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) Conclusions - Brood Ball Success: 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 Conclusions - Brood Ball Success: 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 Mark-and-recapture population estimates and short-term movement patterns of Nicrophorus americanus: 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 Materials and Methods - Mark and Recapture: 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 Materials and Methods - Population Estimates: 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) Slide40: Trapping Area (1 km radius around traps) Materials and Methods - Telemetry Study: 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 Results - Mark and Recapture Data: 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 Mark and Recapture - Movements: 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 Mark and Recapture - Other Statistics: 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) Results - Population Estimates: 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 Results - Telemetry Study: 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 Problems - Transmitter Attachment: Problems - Transmitter Attachment Problems - Transmitter Attachment: 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 Conclusions - Mark and Recapture: 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 Conclusions - Mark and Recapture: Conclusions - Mark and Recapture Study Area Population Estimates: Suggest large increase in population from 2004-2005 Could be due to better conditions during trapping Could be due to change in management on study areas Regional Population Estimates 11,000 to 48,000 N. americanus in Loess Canyons? Conclusions - Radio Telemetry Study: Conclusions - Radio Telemetry Study Close, but not there yet… Transmitters have decreased from 15-20 grams to 0.5 grams in last 10 years…. Need to find ways to get the information on the daytime habitat usage, survival, movements, etc. Overall Conclusions: Overall Conclusions Cedars may limit carrion detection or use by N. americanus and may have increased population of potential competitor, N. orbicollis. Cedars are providing microhabitat conditions that are favorable for Nicrophorus reproduction. Mark and recapture data continues to show that Loess Canyons’ population of N. americanus is among the largest remaining in the nation. Future Conservation Efforts?: Future Conservation Efforts? Results somewhat inconclusive - keep open areas open, at most, thin cedars in other areas Continued addition of State and/or Federally-owned land in the Loess Canyons region Continue to work with private landowners to improve conditions for N. americanus. Long Term Ecological Research (LTER) unit site in the Loess Canyons?? Acknowledgements: Acknowledgements U. S. Fish and Wildlife Service - Section 6 Grant Funding Nebraska Game and Parks Commission - use of vehicle and equipment Gordon Gosnell and NGPC for access to research sites Acknowledgements: Acknowledgements My wife, Michelle, and children (Mikaela, Matthew and Marissa) for sticking with me through the last two years Trapping assistants - Jeffrey Hamik, Brian Sass, Betty Wieck, John Kilpatrick, Mark Staab, Lance Hastings, Mike Fritz, Joseph Harrin and Nathan Svitak Dr. Skinner, Dr. Albrecht and Gerry Steinauer - (Committee) - and Dr. Wyatt Hoback for continuous support and guidance Dan Rochford, my boss, for encouraging me to finish something I started too many years ago Questions??: Questions??