Impact of La Niña vs. El Niño weather patterns on RPQRR coyote diets
by Cade Bowlin, Graduate Research Assistant, Texas Tech University
Adaptive, resilient, and relentless with acute senses of smell, vision, and hearing are traits seldom packaged together in one individual, but the coyote can lay claim to each of the above. Coyotes can make a living just about anywhere, eating just about anything. This prolific North American canid resides in all states of the union except Hawaii. Populations of coyotes occur in remote wilderness and urban jungles such as Chicago and San Francisco.
Coyotes are a common sight on the RPQRR; they comprised 49% of mammalian predators spotted during camera trapping efforts on the ranch during June 2016. Coyotes have been credited with preying on quail and depredating quail nests in the Rolling Plains of Texas. However, it is not known how large of an impact coyotes have on quail populations.
Previous research concerning coyote diets and prey selection on the Rolling Plains has warranted further investigation. Mark Tyson studied coyote diets on RPQRR in 2009-11 as his master’s thesis at Texas Tech University. Tysons’ research was conducted during La Niña weather patterns, with 2011 being one of the hottest, driest years in Texas’ recorded history. The subsequent drought had dramatic effects on the flora and fauna on the ranch and statewide. Bobwhite quail abundance on the ranch reached the lowest numbers since monitoring efforts began on RPQRR.
We hear about La Nina and El Nino on a regular basis. But what causes these phenomena and what exactly are they? The El Nino-Southern Oscillation (ENSO) cycle is comprised of two contrasting phases, La Nina and El Nino weather patterns. Put simply, ENSO describes the fluctuation between sea temperatures in the equatorial region of the Pacific Ocean and atmospheric temperature above this area. El Nino patterns occur when sea surface temperatures are above average. Oceanic temperatures below the mean induce La Nina conditions. Fluctuations in the ENSO can have worldwide weather implications. In our part of the world, El Nino weather patterns typically result in below normal temperatures and above average rainfall. Conversely, La Nina results in hot, dry weather like we experienced from 2010 to mid-summer 2015 (Nielson-Gammon 2016). We are currently in an El Nino phase that has been in place in the Rolling Plains since summer 2015.
A follow up project replicating Tyson’s work during an El Nino, wetter weather pattern is underway on the ranch. This study will assess how major weather patterns affect coyote’s diets and how their diets shift through changing environmental conditions. How do these weather patterns affect coyote diets on a landscape managed strictly for quail such as RPQRR?
Coyote scats have been collected, since Fall 2015, in order to analyze the diets of coyotes on RPQRR focusing on consumption of quail, vegetative mast, and small mammals. Data attained from scat samples will allow analysis of coyote dietary composition. The scat collection route is a 20-mile, continuous loop on the Texas Quail Index (TQI) route on the RPQRR. Coyote scats are collected once monthly with a total of 30 scats collected per month. Scats will be analyzed in the laboratory using a biomass calculation model and frequency of occurrence techniques. Data derived from scat analysis will be used to determine coyote dietary composition on the RPQRR. Using small mammal and quail trapping data, arthropod sampling, as well as monthly vegetation surveys, a determination of food item selection versus availability will be made.
Tyson’s study on RPQRR showed only one quail consumed by coyotes (n=1080 scats). However, quail numbers were also well below historic average on the ranch during the study period. Spring trapping data showed 45.3, 34.1, and 32.2 quail per 100 trap nights during 2009, 2010, and 2011 respectively. Efforts from spring 2016 trapping on the ranch indicated 331.2 birds/100 trap nights (a 10-fold increase from Tyson’s time period). The purpose of this follow-up study is to ascertain whether coyotes are important predators of quail and quail nests during a period when quail and additional coyote food sources are abundant. Additionally, the study will investigate dietary differences of coyotes on RPQRR during La Niña and El Niño weather cycles.
In Tyson’s study, quail were found in less than 1% of coyote scats. Remains from mammals and mast were found in 63% and 67% of scats, respectively. Mast is the edible vegetative or reproductive part produced by woody species of plants and is a key component of coyote’s diets. During the fall of 2011, 96% of scats analyzed by Tyson contained mast. Vegetation surveys have been conducted throughout the duration of the study. Twenty-four, 100-m permanent transects were established along the TQI. Once each month for the duration of the study, all transects were walked and mast assessed. The top five most consumed mast-producing plants from Tyson’s study were monitored (mesquite, prickly pear, hackberry, chittam, and lotebush). The same individual plants were monitored each month to establish mast availability in the study area. Land management practices that encourage growth of mast-producing plants important to coyotes could help relieve pressure on coyote prey species.
In a similar study, Meinzer et al 1973 looked at coyote diets in nearby Knox and King counties. Rodents were the top-ranked prey item consumed by coyotes during the study. The study area is well known for large cow-calf operations; astonishingly no livestock were reported depredated during the study period. Small mammals comprised 24.5% of mean annual diet of coyotes on their study area. Birds and bird eggs made up 1.1% of diets. Meinzer et al (1973) suggested coyote diets vary in a large part due to climactic conditions and patterns. Trapping data on the ranch will help give an abundance estimate of small mammals during the study period.
Preliminary analyses of scats collected Fall 2015 show an abundance of small mammal remains and hair whereas mast is appearing in low abundance in scat samples. No novel items have been found in analysis of scats thus far. Statistical analysis is currently being conducted on vegetation survey data for the study period. It appears low mast production was experienced on RPQRR during 2016. But small mammals (especially cotton rats) have boomed since 2015. A total of 1152 small mammals were captured during summer 2016 trapping efforts on the ranch. These results are drastically different than the 167, 285, and 78 small mammals trapped during 2010, 2011, and 2012 respectively. But winter trapping efforts (still underway on the ranch as of this week) suggest a major crash in small mammal population. The effects on coyote diets, and ultimately quail abundance, are yet to be determined.
Observations on Quail Crops
I’m referring to the anatomical structure, not abundance. A quail’s crop is simply an expansion of the esophagus—it functions as a “zip-loc bag” for seed storage thus affording quail an “eat and run” lifestyle. The longer a quail spends in more open areas, the more vulnerable it is to raptors. With a crop, a quail can eat hurriedly, then retreat to the relative security of a brush thicket as the seeds (and other foods) move through the bird’s digestive tract.
Whenever my dog retrieves a quail, the first thing I do is palpate (“feel”) the crop. Is it full, partially full, or mostly empty? Then, when it comes time to clean the birds, I dissect any “good sized” crops to see what the daily diet consisted of. Inquiring minds want to know.
Thus far I’ve found mostly empty crops, unless the birds had access to supplemental feed (i.e., milo). So, what does the paucity of crop contents mean? Are we on the verge of a “crop failure?” Not necessarily. I attribute the low volume of foods primarily to (a) unseasonably warm temperatures, and (b) a late killing frost (which impacts when broomweed and western ragweed drop their seeds). Birds I’ve looked at thus far have been consuming more greens than I typically expect this early in the season.
As you do your own crop analyses, I’ll wager you’ll discover three things: (a) birds will be feeding much more in late-afternoon than during the morning, (b) birds taken the day after the cold front blows through will have fuller crops than those taken the day of the cold front, and (c) if you have both bobwhites and blue quail, the blues will always have 2-4X more seed volume than bobwhites will, regardless of the time of day you shoot them.
As you come across seeds you can’t identify, take a close-up photo of the crop contents spread out on a paper plate (an iPhone does a nice job) and e-mail it to me at firstname.lastname@example.org. If I don’t know them, I’ll share with my network of “Students of Quail.”
As a reminder, RPQRR is soliciting crop contents of quail harvested across the Rolling Plains (TX & OK) in an attempt to compile a comprehensive seed collection of plants eaten by quail. As you clean birds at the end of the day’s hunt, dissect out the crop and empty the contents into an empty shotgun shell box so they will dry out, then tape the seams with duct tape. Do not put them in a plastic bag as they will mold. At the completion of your season send the box and contents to RPQRR, P.O. Box 220, Roby, TX. The crop content analysis from these samples will constitute our “Seed Appreciation Day” next May.
RPQRR’s Wish List – Can you help?
Our support for quail research comes almost exclusively from private donors. Perhaps you would like to help us help quail. We have need for various pieces of equipment. If you would like to donate, RPQRR is a 501(c)(3) nonprofit foundation, so your donations (cash or in-kind) are tax-deductible. Here’s our current list of needs:
|¾ ton pickup truck
||Pulling trailers, carrying pumper unit for prescribed burns
||Food plot preparation, shredding
|15’ batwing shredder
||Bulk purchase/storage of milo
||Storage of equipment
Weird Quail Watch
On the verge of what many hope will be a record season, I ask that you keep your eyes open for any “weird” quail. “Weird” could include odd plumage, hybrids of bobs and blues, or diseased birds. As you clean your birds always be mindful of birds that are “noticeably” light in weight, or have livers that are discolored (think pickle-loaf). Keep your camera handy for any plumage abnormalities, and a ziploc bag handy if you find any potentially-diseased quail. Either way, please contact me (email@example.com or call my cell @ 325-650-0311) if anything catches your attention. Inquiring minds want to know.
Determining Optimal Levels of Brush Cover for Northern Bobwhite in the Rolling Plains by Brad Kubecka, Graduate Research Assistant
Landscapes that support high densities of northern bobwhite consist of an interspersed mixture of woody and herbaceous cover. Maximum bobwhite densities may be achieved within some range of these cover types, a concept known as “slack.” Thus, landscapes with 10% vs. 40% brush cover could potentially support comparable densities of bobwhites. Recent research in South Texas suggest that landscapes with greater amounts of brush express less variation in the relative abundance of bobwhites during wet and dry years (Parent et al. 2016). In other words, woody cover seemed to cushion bobwhite populations during drought years and/or suppress expansion during wet years. Our objective is to examine associations of bobwhite abundance, woody cover metrics, and precipitation in the Rolling Plains of Texas.
Our study is being conducted on the Rolling Plains Quail Research Ranch (RPQRR) in Fisher County, TX using trapping data (n = 296 traps) collected from November 2008 to March 2017. We feel our intensive trapping database will provide a more in-depth approach than previous studies that have used spring cock call counts as a gauge of landscape configurations and bobwhite abundance. We will calculate relative abundance at each trap site (no. of unique individuals trapped) and quantify woody patch metrics surrounding trap sites (within the buffer of bobwhite’s home range at RPQRR) using satellite technology. Precipitation data will be obtained from on-site weather stations. Our goal then is to determine the influence of woody cover, precipitation, and their interaction on bobwhite relative abundance. Our expected results will provide land managers with an estimate of optimal woody cover and configuration for high densities of bobwhites in the Rolling Plains for both wet and dry years.
Let’s do a quick demonstration. Consider the photos to the right where green represents woody cover and the plot size represents 40 acres (400m x 400m). At this scale, woody cover in all plots is within average flight distance of a bobwhite in the Rolling Plains. Which of the photos has more brush? Which has more edge? Does it matter? Which landscape would consistently hold more bobwhites? During dry years, will areas with fewer, but larger mottes of woody cover sustain higher bobwhite densities? Bobwhite managers often spend much money “sculpting” such patterns (e.g., mottes, strips) on large scales. Through our satellite technology and trapping data, we hope to answer these questions and “tighten” our range of accepted slack. (All photos are drawn to scale and have equal amounts of woody cover. Total woody edge for the strip patterns is 64 units, mottes 15, and sculpted is 51.)
Scaled Quail Restoration to Historic Ranges in the Rolling Plains: Project Update by Becky Ruzicka, Ph.D. candidate
We wrapped up the most intensive part of our monitoring for the year during August on the Knox County translocation site. Since April we have been monitoring our radio-collared hens daily, collecting information on their survival status (i.e. live or dead), movements, and nesting activity. From this point forward we will transition to a bi-monthly monitoring schedule. This will allow us to continue to monitor survival and movement through the fall, albeit at a courser scale. We also plan to conduct trapping to band juveniles, take feather samples for genetic analysis, and potentially document abundance on the two release sites (if our capture rates are high enough).
As it stands now, our survival is at 60% for breeding season. If you were really paying attention, you’d notice this survival percentage is slightly greater than the one I reported in last month’s e-Quail (no, there aren’t birds back from the dead!). We were actually able to locate some of the birds that had been missing and found that they were still alive, thus a slight increase in our total survival as they were added back into the sample. Our farthest recorded dispersers travelled a distance of 5 miles, however most (~70%) stayed within one mile of their release site. Overall, the birds have spread out over an area of approximately 35,000 acres. A formal analysis of these data will be forthcoming in which I will evaluate survival and dispersal as a function of our soft-release and ecoregion source treatments.
Although we are still in the beginning stages of this project, I wanted to take this opportunity to thank the large number of individuals and organizations that have contributed money and resources thus far. I would especially like to thank my field crew: research assistant Drew White, technician Carolin Tappe, and intern Bekah Mullen. Starting in February of this year these ladies have been instrumental in trapping and translocating 388 quail, conducting an occupancy survey over 100,000 acres, and amassing a database of over 4,000 unique observations on our radio-collared birds. Well done!
A New Way to Look at Quail Habitat
It’s called “density gradient modeling.” Think of it as a radar image depicting thunderstorm intensity. In this case being “in the red” is a good thing. Recently John Edwards, a PhD student at Texas A&M University-Kingsville conducted helicopter counts at RPQRR and 3 other area ranches to construct maps illustrating the spatial distribution of bobwhites across the property. The counts at RPQRR are part of a CKWRI research project studying the effects of habitat, climate, and raptors as factors in the quail decline. The map depicted here is a density-gradient map, which uses the covey-detection information provided from the survey such as covey size and location plus additional habitat variables to create a map of bobwhite density across the property. This allows us to evaluate bobwhite density spatially across the landscape. RPQRR’s Brad Kubecka, who is currently pursuing his MS degree at TAMU-K under Dr. Hernandez and me, will be analyzing similar data to better understand how habitat factors (e.g., brush density) affects such density-gradients over the course of the past seven years. Stay tuned; neat stuff.
Operation Idiopathic Decline: Search for the Smoking Gun
The role that disease and parasites may play in quail dynamics has been largely ignored since the 1920s. After the (in our opinion) inexplicable decline of quail in the Rolling Plains, the Board of RPQRF “got serious” about disease and funded a comprehensive project dubbed “Operation Idiopathic Decline.” Currently (as of Feb 2014), the RPQRF has invested $3.4 million into this ground-breaking study of disease and parasites. This webisode explains OID in more depth.