Cranes and other wildlife are stressed by many threats such as predation by humans, sickness, and pollution. Habitat loss, however, is by far the greatest threat. Sandhill cranes are particularly sensitive to this threat because they have special habitat needs. They require roosting as well as feeding habitat. They roost (stay overnight) in shallow wetlands, but they feed in agricultural fields that have been harvested. Cranes some times feed on graslands, but they prefer corn, rice, alfalfa, or wheat fields. These fields need to be within a reasonable proximity to roosting sites, which provide a safe harbor for the night. Some prime examples of crane habitat can be seen at the Cosumnes River Preserve and neighboring farm lands.
How much open space do cranes need?
Visitors to the Cosumnes River Preserve are often surprised by how easy it is to view cranes, and may mistakenly conclude that their abundance on the Preserve is an indication of a prosperous and vigorous population. This may not be the case, as overcrowding generally puts any wild population at increased risk of disease.
Although it is not known exactly how much land is needed to provide adequate space for a healthy population of cranes, the fact that crowding is already occurring indicates how important it is to focus on preserving open space and remaining crane habitat for future generations of cranes and people.
There are two primary threats to Sandhill Crane habitat in the Central Valley today:
- Conversion of large tracts of agricultural land and open space to moderate or low density residential housing.
- Conversion of land presently used for field agriculture to the new use of vineyards, orchards and turf farms.
When open space now used as crane habitat is converted to any kind of urban development it is clearly a losing proposition for cranes. Such conversion typically occurs as the result of land use decisions by cities or the county or our Local Agency Formation Commission (LAFCo). SOS Cranes tries to deal with such conversions on a case by case basis when we can offer useful information that can be considered in the review process.Urban sprawl developments tend to get a lot of attention. There will be public hearings, media coverage and, at times, a vigorous public debate. However there are other land use decisions that can result in massive habitat loss but they occur under the radar and get very little public attention. For example, the City of Galt is in the process of updating its general plan, and is pursuing an expansion to its existing Sphere of Influence to include future development of sensitive habitat areas critical to the survival of Sandhill Cranes and other protected species such as the Swainson's Hawk and Giant Garter Snake. This proposed expansion and development is inconsistent with LAFCo objectives for smart growth. It will not only impact critical habitat but will also limit options for wastewater treatment expansion for sustainable growth of the City, drive up costs for existing Galt citizens, and create more suburban sprawl away from the central Galt city core. Practically no one living outside Galt pays any attention to this process, but if you live in the Sacramento Valley and care about wildlife habitat, this can have a great impact on your interests.
Much the same can be said about the present attempt of the City of Elk Grove to expand its Sphere of Influence southward into open space (including the Cosumnes River 200-year flood plain) and agricultural land. They want to add about 7,000 acres to the city to accomodate projected growth while there are about 6,000 acres of undeveloped land within the existing city limits. The existing undeveloped land within the city limits already has most of the necessary and paid for infrastructure while the rural land they want to expand into does not. Hardly any one outside of Elk Grove is concerned about this. One exception, of course, is the population of the rural areas around Wilton who say, "Wilton is a great place to live. Elk Grove thinks so!"
Vineyards / OrchardsSandhill cranes and other wildlife must depend on privately owned agricultural land for many reasons. First and foremost, the majority of usable open space for most cranes and wildlife is privately held agricultural land. Secondly, for cranes, the source of much of their food is waste grain such as corn, rice and wheat that is grown on such land. But not all agricultural land is welcoming to cranes.The conversion of land used for field crops such as corn or wheat to vineyards or orchards is not seen by many people as a treat to cranes. They see open space converted from one agricultural use to another. It seems innocent enough and all open space is good, right? Wrong. A vineyard is a death trap for cranes. With their six foot wing spans they can not land and take off from vineyards. Besides, they are not interested in going there because there is nothing there for them to eat. Just about the same holds true for orchards.A new threat to crane habitat is the conversion of agricultural land to turf farms. This creates a monoculture with little or no value to cranes.
Climate Change and Sandhill Cranes
Climate change is often refereed to as "Global Warming." Many scientists, however, believe it is better refereed to as "Global Weirding." Massive climate change, as is happening now, can lead to many unexpected and weird changes. While most places may get warmer, some places will get wetter while some will get drier. The microclimate changes are unpredictable. Plants and wildlife will have both winners and losers. At first it may seem that warmer climate will be beneficial to cranes. It could extend their breeding season and reduce the distance they need to fly south to find protection from killing cold. However, at the same time it may decimate some of the sources of their food. This treat will need to be watched closely as it unfolds.
Water ShortageSince the Sandhill crane is a wetland bird, water shortage issues are relevant to it. However, the Sandhill crane is especially sensitive to the loss of wetland because of its unusual roosting behavior. When these cranes roost at night they must be in shallow water with long sight lines. This is a special adaptation that has allowed Sandhill cranes to survive for hundreds of thousands of years. When the crane sleeps in shallow water with long sight lines it is safe from mammalian predators. Shallow water, about three to eight inches deep, is only part way up the legs of these tall birds. However, that same water is almost up to the belly of a coyote! So a coyote trying to stalk a crane will make a lot of noise, be rather uncomfortable, and probably just forget about it. This adaptive technique depends on the ready availability of large bodies of shallow water. Rice fields, for example, are ideal if flooded in the wintertime after harvest. Rice farmers who used to burn rice stubble after harvest have found that flooding their fields not only helps decompose the troublesome rice stubble, but it is compatible with wildlife survival. This example of "wildlife compatible agriculture" is a win-win situation.