Possibly these were trees with roots damaged during construction. Maybe you needed a new septic system or maybe the soil was compacted by vehicles . These trees may now have a limited root system and can be affected by drought. One problem that could result is borers. These are insects that feed in the trunks of stressed trees.
Gardeners often notice sap or sawdust on the trunks of the affected trees.
Regretfully unless it's detected early the trees are often to far gone. You can help trees that are under stress by just giving them good care. Adequate water is all that is needed by most. If you are watering the turf and other landscape plantings this is usually adequate. Where needed sprays available at garden centers can be applied to protect the trunks from insects.