the Elephants and the Bees

Most of us have heard about the birds and the bees, but what about the elephants and the bees?

As human populations continue to expand, African elephant (Loxodonta africana) populations are experiencing substantial declines. Part of this decline is due to human-elephant conflict. Elephants eat a TON of food – roughly 110 tons per elephant per year. That breaks down to around 220 to 880 pounds of food per elephant per day (Shoshani and Foley 2000). With their habitats slowly dwindling and becoming more fragmented, elephants have been increasingly turning toward raiding farmers’ lands to obtain these resources. As a consequence, elephants have damaged crops, depleted food stores and water sources, and sometimes have even threatened human lives (Hoare 2001). Early attempts to manage this conflict involved shooting the ‘problem’ elephants. However, this disturbs other animals and the surviving elephants have been known to respond with hostility toward humans (Vollrath and Douglas-Hamilton 2002). This situation is clearly dangerous for both humans and elephants and calls for a creative solution to this human-elephant conflict.

Image: Roger Le Guen

Inspired by the work of Vollrath and Douglas-Hamilton (2002), this creative solution came from Dr. Lucy King’s idea to use one the elephant’s worst fears to steer them clear of these farmers’ lands. You might be wondering, what could the largest animal on land possibly be afraid of? The answer: bees.

It turns out that even just the sound of African honeybees (Apis mellifera) causes African elephants to immediately retreat (King et al. 2007). During this retreat, these elephants warn other nearby elephants by producing distinct rumble sounds that causes other elephants to flee while shaking their heads, perhaps to prevent bee stings (King et al. 2010). Research has shown that elephants actually have different alarm vocalizations for bees compared to other threats such as humans, which causes elephants to react in different ways (Solstis et al. 2014). This special alarm call and behavioral response to the sound of bees, such as headshaking, highlights the urgency of the threat elephants perceive from these bees. The African honeybee is notorious for being easily aroused and for having large groups involved in aggressive, swarming attacks. African elephants have thin skin with blood vessels near the surface in several locations such as on their belly, in their trunk, around their eyes, and behind their ears. This makes these areas more sensitive to the African honey bees that can and will sting these elephants, and sometimes entire herds are affected by these swarms (Villrath and Douglas-Hamilton). Elephants are known for living in social groups and for having long memories, so it makes sense that such a negative experience can have long-lasting effects.

Image: Chris Eason

A pilot study was conducted by King et al. (2009) that used these bees as a way to deter elephants from raiding farmer’s crops. They accomplished this by constructing beehive fences and placing them around the crops. This preliminary study was remarkably successful at reducing the number of elephant raids of these crops. Not only are the farmers able to significantly reduce the amount of damage to their crops from elephants, but many suspected these fences also deter people from stealing their cattle and later, they were able to collect honey, beeswax, and other products for these hives as an additional source of income (King et al. 2009). News of the success of these beehive fences spread and these fences can now be found throughout several countries in Africa and Asia.

Image of the construction of the beehive fence, included from the preliminary study by King et al. 2009 aiming to prevent elephants from raiding crop farms.

These studies have given rise to a huge conservation effort to mitigate human-elephant conflict and support elephant conservation through the Elephants and Bees Project. This is a collaborative project involving teams of researchers from Save the Elephants, Oxford University, Disney’s Animal Kingdom, and several other institutions. More information, photos, and scientific studies from these efforts can be found on their webpage: http://elephantsandbees.com/

Image: Mario Micklisch

References:

Hoare RE. 2001. Determinants of human-elephant conflict in a land-use mosaic. Journal of Applied Ecology 36(5): 689-700.

King LE, I Douglas-Hamilton, and F Vollrath. 2007. African elephants run from the sound of disturbed bees. Current Biology 17(19): 832-833.

King LE, A Lawrence, and I Douglas-Hamilton. 2009. Beehive fence deters crop-raiding elephants. African Journal of Ecology 47: 131-137.

King LE, J Solstis, I Douglas-Hamilton, A Savage, and F Vollrath. 2010. Bee threat elicits alarm call in African elephants. PLoS One 5(4): 1-9.

Shoshani J and C Foley. 2000. Frequently asked questions about elephants. Elephant 2(4): 78-87.

Solstis J, LE King, I Douglas-Hamilton, F Vollrath, and A Savage. 2014. African elephant alarm calls distinguish between threats from humans and bees. PLoS One 9(2): 1-11.

Vollrath F and I Douglas-Hamilton. 2002. African bees to control African elephants. Naturwissenschaften 89: 508-511.

 

Images:

All images, except the one detailing the beehive fence, were obtained from CreativeCommons.

Beehive fence construction was obtained from King et al. (2009), referenced above.

California: Banning Lead Ammunition to Save their Condors

The critically endangered California Condor (Gymnogyps californianus) is an avian scavenger and North America’s largest flying bird (West et al. 2017).  They have been experiencing population declines since the early 1950s and in 1980, the entire species consisted of only about 30 individuals.  Many doubted that these symbolic birds would do very well in captivity, but in 1987, all 27 of the remaining California Condors were captured and brought to a captive breeding facility. Teams of researchers from organizations such as the U.S. Fish and Wildlife Services, the Los Angeles Zoo, and the San Diego Wild Animal Park came together for these birds and by 1998, there were more than 150 California Condors (Meretsky et al. 2000). Today, there are now five breeding and release facilities in California and Mexico. There are now more than 400 California Condors, and half of these are flying free (National Park Service 2017).

So what was it that caused this species to drop to such small numbers in the first place? When scientists first started looking into this, they discovered that adults had higher mortality rates than immature condors (Meretsky et al. 2000). This was puzzling until they were able to study the tissues of dead condors and obtain blood samples from those that were captured for the captive breeding program. In the mid-1980s, lead poisoning was determined as the leading cause of death in wild California Condors (Wiemeyer et al. 1988).

Lead contamination is responsible for the deaths of millions of birds annually, and the main source of this is from hunting. California Condors are a scavenger species that feed on the carcasses of dead animals, and oftentimes they are feeding on carcasses that have been shot by hunters. Lead bullets, common ammunition used by hunters, shatter into tiny fragments upon impact. Because California Condors are known to scavenge communally, a single carcass containing these bullet fragments can poison several individuals (Kelly et al. 2014). Lead exposure was found to increase during hunting seasons. Sudden, severe symptoms of lead poisoning might include labored breathing, incoordination, and blindness. Chronic symptoms, which take longer to develop, might include changes in migratory movements or changes in bone mineralization, which increases the risk of bone fractures. The final stage of lead poisoning is death (Plaza and Lambertucci 2019).

Although eliminating lead from their environment is critical for the recovery of the California Condor, is it important to note that this is not the only contaminant that is threatening this species. Although California banned DDT in 1972, its influences are very present in this ecosystem today. DDE, a byproduct of DDT that does not get excreted from the body and actually becomes more concentrated over time, is consumed by the condors when they feed on marine mammal carcasses. Once ingested, DDE causes thinner eggshells, which increases the risk of the eggs breaking before the offspring have had a chance to develop (Kiff et al. 1979). Scientists have found that DDE disrupts the endocrine system of California Condors by changing the concentrations of reproductive hormones in their blood and the number of receptors that the hormones can send their signals to, which is what is ultimately causing the thinner eggshells. How lead is influencing the endocrine system in this species is not understood (Felton et al. 2015). Before we can fully address these contaminants that are reducing reproductive success through egg breakage, we need to focus our attention on reducing the amount of lead in the environment so we can increase the number of adults even attempting to nest.

The last two decades have seen the number of free-flying California Condors go from 0 to nearly 200 individuals. The real question is: are these birds still being affected by lead poisoning?

In 2008, California banned the use of lead ammunition for most hunting activities within the wild California Condor range. Annual blood samples found that the percent of these condors with more than 10 micrograms of lead per deciliter of blood was 67% prior to this ban (data from 1997-2008) and 62% after the ban (from 2008-2011) (Kelly et al. 2014). These results indicate that despite this ban, California Condors are still experiencing chronic exposure to lead poisoning. Because of this, California has decided to enact a state-wide ban on the use of lead ammunition for hunting, which is set to go into full effect on July 1, 2019. Perhaps this will be the key to the success of one of our country’s longest-running conservation programs. 

 

 

References:

Felton RG, CC Steiner, BS Durrant, DH Keisler, MR Milnes, and CW Tubbs. 2015. Identification of California Condor estrogen receptors 1 and 2 and the activation by endocrine disrupting chemicals. Endocrinology 156(12): 4448-4457.

Kelly TR, J Grantham, D George, A Welch, J Brandt, LJ Brunett, KJ Sorenson, M Johnson, R Poppenga, D Moen, J Rasico, JW Rivers, C Battistone, and CK Johnson. 2014. Spatiotemporal patterns and risk factors for lead exposure in endangered California Condors during 15 years of reintroduction. Conservation Biology 28(6): 1721-1730.

Kiff LF, DB Peakall, and SR Wilbur. 1979. Recent changes in California Condor eggshells. Oxford University Press 81(2): 166-172.

Meretsky VT, NFR Snyder, SR Beissinger, DA Clendenen, and JW Wiley. 2000. Demography of the California Condor: Implications for Reestablishment. Conservation Biology 14(4): 957-967.

National Park Service. 2017. Condor Re-introduction & Recovery Program. https://www.nps.gov/articles/california-condor-recovery.htm

Plaza PI and SA Lambertucci. 2019. What do we know about lead contamination in wild vultures and condors? A review of decades of research. Science of the Total Environment 654 (1): 409-417.

West CJ, JD Wolfe, A Wiegardt, and T Williams-Claussen. 2017. Feasibility of California Condor recovery in northern California, USA: Contaminants in surrogate Turkey Vultures and Common Ravens. The Condor: Ornithology Applications 119(4): 720-731.

Wiemeyer SN, JM Scott, MP Anderson, PH Bloom, and CH Stafford. 1988. Environmental contaminants in California Condors. The Journal of Wildlife Management 52(2): 238-247.

 

Images:

All images were taken by former coworker, Louise Prévot, in Marble Canyon, AZ.