By Sara Kuruvilla, Jennifer Del Tin, Mary-Elizabeth Pennington & Teslyn Heron
There are 6 subspecies of Sandhill Cranes including greater, lesser, Cuban, Mississippi, and Canadian (Gerber & Kendall, 2016). The Cuban subspecies does not migrate and is currently considered federally endangered, along with the Mississippi Sandhill Cranes and Florida cranes (United States Fish and Wildlife Service, n.d.).
Based on early historical reports, the first account of Sandhill Cranes was in the 1800s by John Hunter, a Plains explorer in North America, who reported sight of the Sandhills on the Central Platte (modern day Nebraska, USA). Although this area was prior frequented by thousands of colonizers moving westward along the Oregon and Mormon Trails, the timing of their journey fell during late spring when the river was safer to cross over. As the Sandhills would have already departed before this time, it is of no surprise that there was no mention of the birds in journals of the early colonizers (Johnsgard, 2002). Within the same century, the population of Sandhills started to decline due to unregulated hunting and habitat loss. Fortunately, their numbers later increased significantly after the signing of the Migratory Bird Act in 1918 (U.S. Fish & Wildlife Services, 1984); thereby removing the migratory species of Sandhill Cranes from the endangered species list (Government of Canada, 2015).
Special Historical Fact: According to the International Crane Foundation, the Sandhill Crane may possibly be one of the oldest surviving bird species. This assumption is based on the discovery of a crane fossil (originating from the Pliocene period) found in Nebraska, that was found to have the same skeletal structure as the modern Sandhill Crane.
The Sandhill Crane is considered a ‘K’ strategist because they live long lives, have few offspring each year, and extended parental care for their young. ‘K’ strategists can be wiped out easier than ‘R’ strategists, and they take longer to recover. This is why after the Migratory Bird Treaty Act of 1916 was introduced, their population grew slowly until they were no longer considered to be a species at risk.
Historically, Sandhill Cranes prefer open wetland habitats when they are breeding, while non-breeding cranes prefer open prairie habitats (The Cornell Lab of Ornithology, 2016). Agricultural lands (such as the corn fields) that Sandhill Cranes are often found foraging in, simulate these open types of habitats. They prefer digging in the ground for their food and the waste corn that they thrive on in agricultural fields is accessed in this way (Harner, Wright, & Geluso, 2015).
Although restoration efforts have increased Sandhill Crane numbers, with the growing human population and therefore a higher agricultural demand, wetlands are still decreasing and are becoming more absent from areas that serve as habitats for the cranes (Lacy, Barzen, Moore, & Norris, 2015). This in turn, causes Sandhill Cranes to turn to agricultural lands as a staple habitat as well as food source. Along with this issue, according to Matt Seabrook- a grain farmer from Ontario, Canada- the presence of the Sandhills in agricultural fields pose an additional threat. Due to their large stature, they tend to flatten standing crops with their large feet, therefore providing migratory Geese with landing access to the fields and hence causing further destruction to the crops (Kerr, 2016).
Critical Assessment of Management Options
To establish a more positive relationship between the Sandhill cranes and the farmers who provide the needed habitat, several management options are being explored:
- Repellents: The International Crane Foundation is helping to develop a new technique to treat corn seeds with a deterrent before the seeds are planted. In response, foraging Sandhills avoid treated seed but remain in the field to feed non-destructively on other foods. The new repellent known as Avipel, is commercially sold by its manufacturer Arkion Life Sciences (International Crane Foundation, n.d; Lovell, 2012).
- Exclusion: This involves the installation of barriers such as fencing and overhead grids, to prevent the Sandhills from entering an area. This technique may be effective to prevent property damage in smaller areas such as family gardens and windows (Sandhills attack their own reflection thinking it is a competitor). Unfortunately, for larger areas such as airports and farms, barriers would be ineffective and the costs would be too high (Lovell, 2012).
- Harassment: This method may be the most effective in deterring the Sandhills, but care must be taken to use a variety of devices (pyrotechnics, Airdancers, air horns, drones) and not follow a set schedule, lest the birds become accustomed to the disturbance. The keys to a successful harassment operation are timing, persistence, randomness and diversity (Lovell, 2012).
- Hunting: Although hunting may be the most useful form of management- apart from the owner requiring a valid gun license- a federal permit with state authorization would be required in order to hunt the birds for the purpose of protecting property. Along with this, hunting may be useful in removing an individual Sandhill, but crop damage over large areas is generally carried out by large flocks of Sandhills Cranes (Lovell, 2012).
- New Hunting Regulations: In order to implement more effective and sustainable hunting regulations, more information needs to be known about the total population sizes of Sandhill Cranes, their annual mortality, and their annual recruitment (Krapu, 2011). The Sandhill Crane has many subpopulations depending on the region (Mid-West, Pacific Flyway, Rocky Mountain, Eastern, etc.), and some of these subpopulations overlap. This is problematic because some of these subpopulations are smaller in size and it is not permitted to hunt them (Krapu, 2011). Surveys will be beneficial to obtaining this crucial information for the management of Sandhill Cranes and reduce the negative impact that they have on agricultural lands (Krapu, 2011). This could prove to be costly based on the amount of resources that would be needed to survey the population, such as GPS trackers and qualified personnel.
- Guard Dogs: The usage of pets such as guard dogs could be considered as a greener and less expensive form of harassment, although the risk is high as Sandhill Cranes have been known to successfully drive away predators of similar sizes to dogs.
- Co-existence: In some states and provinces farmers will receive compensation for crop damage by Sandhill Cranes, Ontario however is still in the process of approving this because population numbers are unknown (Harris, 1996 & Saskatchewan Crop Insurance, n.d.). As well, there are currently no hunting regulations in place to allow the harvest of Sandhill Cranes in Ontario (Ontario Federation of Anglers and Hunters, 2014). There are actions that farmers can take in order to create a better coexistence between Sandhill Cranes. These actions could include scaring tactics, relocation of agricultural lands, or diversionary agricultural lands (Nilsson, Bunnefeld, Persson, & Månsson, 2016). Scaring tactics have proven effective in keeping Sandhill Cranes off agricultural land and can include propane cannons, flags, or scarecrows (Nilsson et al., 2016). The issue with scaring tactics is that although they are effective at steering birds away from the property they were utilized on, they often just relocate the birds to someone else’s farm (Nilsson et al., 2016). Agricultural damage is more common in lands within close proximity to wetlands or other protected areas (Nilsson et al., 2016). It may not be feasible to ask farmers to relocate their livelihood away from these areas, but if possible it would lessen the impact of Sandhill Cranes on agriculture. Another successful tactic is the creation of diversionary agriculture lands, which is essentially an open field in which birds can graze with no economic impact (Nilsson et al., 2016). Relocating birds to these areas by using scare tactics will decrease the number of birds grazing in valuable agricultural lands.
- Falconry: Alternatively, trained raptors could also be used as a management option. Although there are no known reports of using raptors to deter Sandhill Cranes specifically, the raptors are being used to deter other pests. In Canada, the US, and even Dubai, pest control companies use raptors to deter pigeons, raccoons, seagulls etc. In Washington, US, an Aplomado falcon was used to patrol a blueberry field at a farm (The Seattle Times Staff, 2014; Choksi, 2015).
According to the Government of Ontario (2016), the types of birds that can be used for falconry within Ontario are divided into Ontario native birds and non-indigenous birds. The requirements for hunting with them are:
- Ontario native birds:
i. A small game hunting license
ii. An identification band on each bird
iii. Maintain a log book, as outlined in as outlined in Ontario Regulation 668/98 27.(1)
iv. An Apprentice Falconry License (or) a General Falconry License (or) a Commercial Falconry License. Conditions apply for each license type.
- Non-indigenous bird
i. A small game hunting license
ii. An identification band on each bird
iii. To maintain a log book, as outlined in as outlined in Ontario Regulation 668/98 27.(1)
Table 2: A visual comparison between each of the factors discussed in the Critical Assessment of Management Options. Although the co-existence between the Sandhill Cranes and the farmers is the most preferred option, it would be a great challenge to gain and assign land to be solely used by the Sandhills. Falconry may be the most effective option, but method is still yet to be tested with Sandhill Cranes (Created using MS Paint and MS Word, tractor image from Clipart Kid, 2016) .
|Management Strategy||Costs||Advantage||Disadvantage||Factors to Consider||Overall Effectiveness|
For large scale
For small scale
|Size of area to be covered||+–|
|$$$||Inconvenient in the long run||
|Hunting||$$||Cannot use for whole flock||
|Implement new hunting regulations to suit the population size||$$$||
Costs and equipment to monitor population size
|Guard Dogs||$||Dogs could get attacked||
Yet to be tested
|Co-existence between farmers and Sandhill Cranes||$$$||Land set aside for just the Sandhills||
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