Written by Sara Kuruvilla, Jennifer Del Tin, Mary Pennington, and Teslyn Heron
Ecological Profile: Sandhill Crane, Antigone canadensis
Sandhill Cranes, Antigone canadensis, is a species of bird that belong to the Gruidae family, with six subspecies. They are the most common cranes in the world and occur mostly in North America. They are migratory birds and because of this both their summer and winter range must be considered (National Geographic, 2017). During the summer months, these birds are found predominantly in North America with a small range occurring in Siberia (National Geographic, 2017). As seen in Figure 1, their winter range consists of more southern areas such as Florida, California, Texas, Utah, Mexico, and Cuba (National Geographic, 2017). There are a few populations that nest in Mississippi, Cuba, and Florida that stay in these areas year-round and do not migrate (Kaufman, n.d.). It has also been found that some individuals are now nesting further north than they have in the past (Kaufman, n.d.).
Figure 1: Global Distribution of Sandhill Cranes, Antigone canadensis (Base map ESRI, range based on BirdLife International, 2016).
Figure 2: Ontario distribution of the Sandhill Crane (Antigone canadensis) The Sandhill Crane’s range is found in northern Ontario and a small portion of southern Ontario (Basemap: ArcGIS software; Range modified from Kaufman, n.d. & The Cornell Lab of Ornithology, 2016).
The habitat of the Sandhill Crane varies based on the region, but they will typically nest in areas surrounding marshes or bogs (Kaufman, n.d.). They prefer these areas because their nests are built with cattails, sedges, grasses, and bulrushes (The Cornell Lab of Ornithology, 2016). Breeding birds prefer the edges between wetlands and upland habitats, while non-breeding birds prefer more open and grassy areas (The Cornell Lab of Ornithology, 2016). Their winter habitat consists of shallow lakes and rivers during the night, and irrigated croplands, pastures, grasslands, and wetlands during the day (The Cornell Lab of Ornithology, 2016). Their preference toward more open areas has been known to cause crop damage; this is because they often dig in the soil for tubers (National Geographic, 2017).
Potential for Infestation
Sandhill Cranes lay two eggs in a ground nest that is 30-40 inches wide, and constructed using surrounding vegetation. The male then stands guards of the nest the majority of the time. The eggs hatch in about one month, and the young are independent two months after hatching. They will join the adults in migration that season, and stick close to their parents for 9-10 months (National Wildlife Federation, 1996-2017). They can begin reproducing at 2 years of age, and the adult Sandhill Cranes can live for as long as 36 years. This species, as well as other bird species, share “R” and K-strategist qualities, but is considered to be closer to a K-strategist due to the fact that they produce few offspring at once, extended parental care, and a long lifespan (see Table 1) (Rafferty, 2011).
Table 1: Reproductive strategies of the Sandhill Crane, Antigone canadensis, showcasing the typical reproductive strategy of K-strategists. (Table adapted from Feltham, 2016) (Sandhill Crane sources: Lacy, Barzen, Moore, & Norris, 2015; Molles & Cahill, 2014, p. 245; Rafferty, 2011 & 2014; The Cornell Lab of Ornithology, 2016)
|Population Growth||High||Low||8.39% increase from 2003-2013|
|Mortality||Variable and unpredictable||More constant and predictable||Not variable, constant|
|Lifespan||Short||Long||20 years in the wild|
|Adult Size||Small body size||Large||Large body size|
|Clutch Size||Large||Small||Small – Maximum of 3 eggs|
|Parental Investment/Care||Very little if any||Required||→ Both parents incubate the eggs.→ The males take responsibility for guarding the nest→ Hatchling are precocial→ The juveniles stick to their parents 9-10 months after hatching→ Age at first flight is 65-75 days|
|Age of Maturity||Most reproductively mature individuals reproduce successfully||Few reproductively mature individuals or some reproduce successfully||While some start breeding at the age of 2, most start at the age of 7|
|Frequency of Reproduction||Once to multiple times over short time period||Multiple times but over a prolonged period||1 brood per year, breeding pair mate for life|
Sandhill Cranes exhibit the characteristics of having a Type II survivorship curve. During the first 9-10 months of their lives, the investment and care of their parents ensures a low mortality rate for young Sandhill Cranes during the developing months of their lives (Kaufman, n.d.).
Figure 3: Displayed in this figure are the three different survivorship curves with examples of species that demonstrate each of them. Sandhill Cranes demonstrate a Type II survivorship curve because they have an equal rate of mortality regardless of their age (Encyclopaedia Britannica, 2016).
Sandhill Cranes are migrating birds, which has an affect on their dispersal. In the summer months, they are viewed in more northern climates and in winter they travel south. They can travel up to 402 km in one day, at speeds of up to 56 Km per hour, and they generally stop in the same spots each year (Perron, V., 2014). Even though today this species is the most common crane in the world, but they are vulnerable to habitat loss in the future (Kaufman, n.d.). From 1966-1977 most of the wintering Sandhill Cranes were counted in central Florida, but by 2002-2013 their wintering range has expanded north by 158 km. Sandhill Cranes have also been observed migrating in areas further west than Florida a lot more frequently (Harner, Wright, & Geluso, 2015). In mid-February, Sandhill cranes rely on the Platte River as a key stopping point for 3-4 weeks, to regain energy and nutrients before they continue migrating north (Seecan, G., 2016). The cranes use the open sections along the banks of the river to roost. Without this area, the cranes would not have enough stored energy to be able to complete their migration (Kessler, Merchant, Shultz, & Allen, 2013).
Figure 4: Using an aerial thermal infrared video system, images were uploaded to a geographical information system (GIS) to showcase roosting sites of the Sandhill Cranes along the Platte River. Video from high altitudes was used to record roosting flocks across the entire width of the river, while video from low altitudes was used to record the spatial density of the cranes within each roosting flock (U.S. Geological Survey).
In the early 1900’s, these birds were nearly extirpated from areas in the United States, with approximately only 25 breeding pairs left in Wisconsin. Protection efforts allowed these birds to expand their population, and by 1996 numbers exceeding 30,000 were observed. Below, Figure 5 demonstrates the increase in population size over the years (Lacy et al., 2015). While Sandhill Cranes are currently quite an abundant species, they may become more threatened in the future. This is because 80% of Sandhill Cranes utilize a 180 km stretch along Nebraska’s Platte River as their migration route and this area is facing a lot of development pressures which may cause issues for the Sandhill Crane in the future (Harner et al., 2015). In some areas, overhunting is causing issues for these birds as well as commercial and residential development in some of the southern areas that have become year round habitats for the Sandhill Crane (International Crane Foundation, 2017).
Figure 5: Displayed in this graph is the Breeding Bird Survey of Sandhill Cranes conducted in the United States and Canada (Lacy et al., 2015).
Sandhill Cranes are opportunistic eaters and will indulge in macroinvertebrates, rodents, frogs, snakes, plants, and grains. This can pose a problem to farmers because the species will dig in agricultural fields for tubers, which in turn causes crop damage. During their layover in Nebraska, they can consume as much as 1, 600 lbs of waste corn. Sandhill Cranes are only territorial during breeding season, usually beginning around mid-March. This is to ensure there isn’t a depletion of food sources so that they can have healthy young that survive into adulthood. They are quite social during the fall and winter months (Bennett & Bennett, 1992).
Predator species of the Sandhill Crane include coyotes, bobcats, and eagles, but the biggest threat is human influence and the degradation/destruction of marshlands (Oklahoma Department of Wildlife Conservation, 2011). Along with these pressures, The Sandhill Cranes also face issues regarding invasive wetland plant species such as the Purple Loosestrife (Lythrum salicaria) and the Common Reed (Phragmites australis). According to author Sierra Harris, these invasives have detrimental effects to the Crane’s main roosting area along the Central Platte River located in Nebraska, USA (Harris, S., 2014). Recently, the plants have been taking over the riverbank and have even caused the sandbanks to become anchored, thus in turn changing the surrounding habitat and the river’s overall hydrology. With this alteration to the river’s natural process, and the decrease in plant diversity (and the eventual formation of a monoculture), fewer number of birds have been found in the invaded wetland areas. Land management and control treatment methods like burning and herbicide applications have been carried out annually but it only seems to decrease the abundance of the invasives, and does not completely eliminate them.
BirdLife International. (2016). Antigone canadensis. The IUCN Red List of Threatened Species 2016: e.T22692078A93336581. Retrieved from: http://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T22692078A93336581.en
Encyclopaedia Britannica. (2016). Survivorship Curves. Retrieved from https://www.britannica.com/science/survivorship-curve
Harris, S. (2014). Sandhill Cranes Vs. Invasive Species | PBT. Retrieved February 04, 2017, from http://plattebasintimelapse.com/2014/08/sandhill-cranes-vs-invasive-species/
Feltham, J. V. (2016). Species Management Strategy. Gray wolf, canis lupus. Retrieved January 27, 2017.
Kaufman, K. (n.d.). Sandhill Crane. Retrieved from http://www.audubon.org/field-guide/bird/sandhill-crane
Kessler, A. C., Merchant, J. W., Shultz, S. D., & Allen, C. R. (2013). Cost-effectiveness analysis of Sandhill crane habitat management. The Journal Of Wildlife Management, (7), 1301.
Lacy, A. E., Barzen, J. A., Moore, D. M., & Norris, K. E. (2015). Changes in the number and distribution of Greater Sandhill Cranes in the Eastern Population. Journal Of Field Ornithology, 86(4), 317-325. doi:10.1111/jofo.12124
National Geographic. (2017). Sandhill Crane. Retrieved from: http://animals.nationalgeographic.com/animals/birds/sandhill-crane
Molles, M.C., & Cahill, J.F. (2014). Ecology Concepts and Applications. Toronto, Canada: McGraw-Hill Ryerson Limited.
Perron, V. (2014). Sandhill Crane Migrations Revealed by Satellite. Retrieved from: http://www.opb.org/television/programs/ofg/segment/sandhill-crane-migrations-revealed-by-satellites/
Rafferty, J. (2011). K-Selected Species. Retrieved from https://www.britannica.com/science/K-selected-species
Rafferty, J. (2014). R-Selected Species. Retrieved from https://www.britannica.com/science/r-selected-species
Seecan, G. (2016). Sandhill Crane Migration. Retrieved from: http://www.nebraskatravels.com/sandhill-crane-migration.html
The Cornell Lab of Ornithology. (2015). Sandhill Crane. Retrieved from: https://www.allaboutbirds.org/guide/Sandhill_Crane/lifehistory#at_habitat
U.S. Geological Survey (USGS). (2016). Assessing Sandhill Crane Roosting Habitat along the Platte River, Nebraska. Department of Interior. Retrieved February 04, 2017, from https://pubs.usgs.gov/fs/2005/3029/
Written by: Sara Kuruvilla, Mary Pennington, Jennifer Del Tin, Teslyn Heron.